Reporter Kim Gittleson is inside City Hall for Mayor Bloomberg’s press conference to announce the surprise departure of Schools Chancellor Cathie Black and the appointment of Deputy Mayor Dennis Walcott to replace her. Our coverage of the leadership change will go on all afternoon.

2:30 p.m. Walcott’s appearance at Tweed Courthouse has come to a close and so, too, will our live-blog. We’ll have continued coverage of the Department of Education’s leadership changes later today.

2:20 p.m. Walcott joked that he had worn a “Walcott path” between City Hall and Department of Education headquarters that he’ll now have to travel in reverse — and that he wants to start right away. “The passion of my soul is committed to the children of New York City,” he said.

Walcott said he already spoke to UFT President Michael Mulgrew by phone and left a message for principals union president Ernest Logan this morning. Next, he’ll turn his attention to advocating in Albany for city schools funding, he said.

Walcott would not say when Bloomberg first contacted him about taking the job. Asked if he was surprised to have been offered it, Walcott said, “I’m always surprised. I never take things for granted.”

On the question of whether the city’s school priorities would change, Walcott said, “We have a collective responsibility to continue reforms we’ve been implementing over the last nine years. … Policies will be basically the same.” He specified that he would not revisit school closure decisions also said, “I’m a believer in all types of schools,” including charter schools.

“I serve at the pleasure of the mayor,” he emphasized.

Summing up the day, Walcott told assembled education department staff members and reporters, “I”m a happy camper.”

2:15 p.m. Concluding his remarks, Walcott thanked Black for her service and said she called him this morning. Black is “very jazzy — she really is a trailblazer,” Walcott said, adding that he plans to continue to work both with Black and with Joel Klein.

Walcott declined to answer questions from reporters about Black. “I’m not here to talk about Cathie,” he said.

2:08 p.m. Kim (who is battling strep throat) is back at Tweed Courthouse, where Walcott is getting a standing ovation from a packed house of DOE officials. The new chancellor is in good spirits, smiling widely and cracking jokes. “Next week you’ll see me over here permanently,” he said. “They’re going to have to tie me down.”

Walcott took questions from staff before turning his attention to the gaggle of reporters.

2:05 p.m. U.S. Education Secretary Arne Duncan is sitting out the debate over who should lead the city’s schools. Here’s his statement: “New York has a lot of hard work ahead as they continue the drive for education reform. Our children only get one shot at a good education, so it’s time for everyone to come together to do the right thing for kids.”

Yesterday, Duncan called attention to the city’s high school dropout rate during an appearance at a conference in Harlem run by the Rev. Al Sharpton.

1:57 p.m. More from Kim at UFT headquarters: Michael Mulgrew’s first words upon greeting reporters were, “New York politics. Here we are again.” Mulgrew says he hopes the leadership change will give the union a chance to change “some education policies we’ve been outspoken about.” And he says at least one good thing came out of Black’s brief tenure at the DOE: “Community members and parents are more engaged.”

Mulgrew says he has known Walcott for many years and looks forward to working with him as chancellor. But his praise is more tempered than much of what we’ve heard today (scroll down for examples). As Bloomberg’s top education aide since 2002, Walcott has stood behind the mayor through many fights with the union, including the current one over layoffs and how they should be done.

Nor does he have much to say about Black herself: “I wish her well as I do anyone.”

1:54 p.m. No one has seen Cathie Black today — but the Twitter user who goes by CathieBlackDOE2 offers one (completely fabricated) version of what the former chancellor might be doing: “Lunch at Masa, dinner at Per Se, running up and down Park Avenue naked in between. Free at last! Free at last!”

A Twitter account purporting to be Dennis Walcott’s has also cropped up. Its first dispatch, sent early this morning? “To be honest, I don’t have the best feeling about this.”

Our vote for best Black-related Tweet of the day is this one from City Hall News: “The ‘Last In, First Out’ headlines kinda write themselves, huh?”

1:45 p.m. Kim has made the quick trip down Broadway to United Federation of Teachers headquarters, where union president Michael Mulgrew is speaking to reporters. Mulgrew is refusing to answer questions about whether he’s happy to see Black gone from the Department of Education, Kim reports.

Asked to grade Black’s performance as chancellor, Mulgrew said, “She wasn’t in the class for the full semester so it wouldn’t be appropriate for me to give her a grade.”

1:20 p.m. “Cathie Black” is currently the seventh-most heavily Tweeted term in the United States.

1:15 p.m. Some elected officials are so pleased to see Cathie Black out as chancellor that they are throwing a going-away party on the steps of Tweed Courthouse this afternoon. City Councilman Charles Barron and Assemblywoman Inez Barron, his wife, both vocal critics of the Bloomberg administration’s school policies, will celebrate Black’s departure but also call on the mayor to let New Yorkers play a role in selecting her replacement.

Charles Barron: “We the people are vindicated. We were right from the beginning and this shows when you stick together and are persistent, you can win in the struggle for justice. Now we call on the mayor to sit down with us and listen to our suggestions for candidates to replace the former chancellor.”

Barron went on: “With all of his mistakes, maybe Mayor Bloomberg should resign too.”

1 p.m. The Department of Education just sent out an alert to reporters advertising the press availability Walcott announced. Walcott will be speaking to Department of Education staff at Tweed Courthouse, not just to reporters.

12:55 p.m. Pretty sure that the press release from the “Deny Waiver Coalition,” a group that lobbied for the state to stop Cathie Black from becoming chancellor, is the first to signal caution on Walcott’s appointment. It reads:

The Deny Waiver Coalition called for a national search to find the best Chancellor candidate. That has not happened. The Coalition demanded a Chancellor with proven experience at leading public schools or school systems. New York City still does not have that. The Coalition advocated for transparency in the Chancellor selection process. That has yet to happen.

12:50 p.m. Pinch-hitting from New Orleans, where she’s attending the Education Writers Association conference, recent GothamSchools alum Maura Walz spoke to Board of Regents Chancellor Merryl Tisch, who joins the chorus of officials welcoming Walcott with open arms.

Tisch said Bloomberg called her this morning to tell her about the personnel change. “He was very direct,” she said “He said he had a conversation with Cathie and they both agreed that Dennis was going to do this role. We basically spoke about Dennis.”

About Walcott, Tisch said: “I have a longstanding working relationship with Dennis. I believe there will be no issues of transition here. He is articulate with the issues, he is articulate in the communities. … I believe he is someone who is going to restore a sense of calm.”

Tisch went on: “I think that Dennis is being brought in to do a task that he is eminently qualified to do. It will be very good that it’s not up in the air. If you’re asking me should the mayor have done a search … I would say no.”

Why exactly Walcott requires a waiver from the Regents to become chancellor isn’t clear even to her, Tisch said, but she promised that it would come quickly — although she implied that she had not yet received a request for one.

“It’s interesting that Dennis does need a waiver, but I imagine that would be a very pro-forma waiver,” she said. “I assured [Bloomberg] that there would be no reason as best I can see that that would not be granted quickly. In other words I hope that the city lawyers get us the waiver request right away.”

12:35 p.m. More evidence that Black’s resignation wasn’t planned for long: Sources in and around the city’s education department told GothamSchools that they were still scheduling events with her up to last night.

We are also hearing that department insiders are pleased with Walcott’s appointment.

12:28 p.m. Many questions are still unresolved: Why exactly does Walcott require a waiver from the state to become chancellor? What will be the role of Shael Polakow-Suransky, the DOE official promoted to Chief Academic Officer as a requirement before the state would allow Cathie Black, who did not have an education background, to take the job? (Bloomberg did say he’d stay on in that position.) And why didn’t Bloomberg pick Walcott, who knows the city’s school policies well, when Joel Klein resigned?

These questions are likely to be among the first asked at 2 p.m., when Walcott is set to take questions from reporters. (When Walcott announced he’d be taking questions then, a City Hall press official appeared to be surprised, Kim reports.)

12:25 p.m. The official press release from the mayor’s office has just hit our inboxes. Again, it emphasizes Walcott’s experience in city education policy and his family ties to the school system.

The press release also clarifies Walcott’s status within city government. “Upon approval from the New York State Board of Regents, Walcott will step down as Deputy Mayor for Education and Community Development,” the release says.

12:20 p.m. GothamSchools reporter Anna Phillips reached Eric Nadelstern, who left high high-ranking position at the DOE in January, shortly after Black took over. Nadelstern said he thinks Black made the decision to step down on her own and that the deck was stacked against her from the start.

Said Nadelstern:

I think everyone was caught by surprise although you and your colleagues in the press have not been kind to her and it’s been a very difficult transition and I would imagine it was her decision and not the mayor’s. I do think she came in at a very difficult transition period and I think she came in with the best of intentions to do the necessary work and I think was overwhelmed by the circumstances. The circumstances of a third-term mayor with waning popularity, a press corps that felt that it did not have access to the last chancellor and was resentful that it didn’t have more access to the new chancellor, and a financial situation that threatened not only the stability of the system but the ability of schools to continue to the gains that have been made.

12:10 p.m. Three takeaways from the press conference that just ended: Bloomberg and Black met this morning and agreed that Black should step down. Bloomberg is hoping the leadership change will redirect redirect attention that has focused on Black’s leadership onto city students. And Walcott was Bloomberg’s first choice to replace Black.

12:05 p.m. Dozens of press releases flew into my inbox during the press conference, with reactions from elected officials, the principals union, charter school advocates, and more. They are uniformly glowing about Walcott’s appointment.

“Some months ago, I recommended that Dennis be named chancellor and I am delighted that this has happened today,” said principals union president Ernest Logan in a statement.

Some months ago, of course, was when Bloomberg named Cathie Black chancellor without warning.

12:01 p.m. The blitz of a press conference is over, and Walcott says he’ll take questions later. Jokes a reporter, “He’s got a body guard of 10-year-old children.”

11:56 a.m. Walcott will be serving as schools chancellor, but the deputy mayor position that he is vacating will go unfilled, Bloomberg says. Bloomberg said that even though he has a master’s degree in education, which Cathie Black did not, Walcott will still require a waiver from the state to take the job. Bloomberg says he is hoping that waiver to be granted quickly.

Bloomberg says he doesn’t know whether Black is still legally the city’s schools chancellor. But Walcott is assuming her responsibilities immediately.

Walcott will continue to draw the salary of a deputy mayor, which is less than the $250,000 a year that chancellors are paid.

11:53 a.m. Here’s an interesting tidbit: Bloomberg said he talked to Joel Klein before offering the job to Walcott.

11:52 a.m. Bloomberg is back, but he is declining to answer questions about the timing of the decision to remove Black or about Black herself. Black is nowhere to be seen.

But he says, “The story had become about her and away from the kids.”

11:50 a.m. The front row is reserved for members of the student government at PS 10, who apparently already had an appointment with Walcott to make waffles. That will happen next week, Walcott promises.

11:47 a.m. Now Walcott himself is taking the podium. Citing not three but four generations of public school patrons in his family, Walcott says he will build on the progress made under Bloomberg’s tenure and will build on the reforms that have already been made.

“I’m a believer in reform. I’m a believer in this mayor,” Walcott says.

“I want to thank the mayor for asking me to take the position,” he says. “I consider myself very blessed and very lucky to be asked. Me — I’m just a guy from Queens whose parents were raised in Harlem. … I’m just a city guy.”

Walcott goes on to say that he is extremely familiar with the city’s schools. “I have visited probably hundreds and hundreds of our schools, walked the corridors, held the hands of children.”

11:46 a.m. In contrast to Black, Dennis Walcott knows the city schools well, Bloomberg emphasizes, noting that Walcott’s children attended public schools and a grandchild is a public school student now. Walcott himself is a public school graduate.

11:43 a.m. Bloomberg says Cathie Black’s tenure hadn’t gone as planned — and that he is to blame. ”I take full responsibility for fact that this hasn’t worked out as expected,” he said.

He said he met with Black early this morning and they mutually agreed that it was in the city’s best interest for her to step down as chancellor.

11:40 a.m. We are inside City Hall, where Mayor Bloomberg’s press conference is minutes away from starting. Our reporter, Kim Gittleson, is crammed in along with hordes of reporters and several breathless city staffers. From first blush it looks like Black’s departure is as much a surprise as Joel Klein’s was in November.