Hadn't heard that one before...but here is what I found:
Michelle Obama organized a University of Chicago panel about Bill Ayers's crime book in November 1997, just as the battle over the juvenile justice bill was heating up. That panel featured appearances by some of the key figures discussed in Ayers's book, along with Obama himself, who was identified in the press release as "working to block proposed legislation that would throw more juvenile offenders into the adult system." In effect, then, this public event was a joint Obama-Ayers effort to sink the juvenile justice bill-Obama's decision to plug Ayers's book in the Chicago Tribune the following month was part of the same political effort.
See also:
The Obama-Ayers Top Ten: Highlights of the 20 year Obama-Ayers Connection
That Guy Who Lives in My Neighborhood: Behind the Ayers-Obama Relationship
http://www.nytimes.com/2008/05/11/us/politics/11chicago.html?pagewanted=3&_r=1
Mr. Obama also fit in at Hyde Parks fringes, among university faculty members like Bill Ayers and Bernadine Dohrn, unrepentant members of the radical Weather Underground that bombed the United States Capitol and the Pentagon to protest the Vietnam War. Mr. Obama was introduced to the couple in 1995 at a meet-and-greet they held for him at their home, aides said.
Now, along with Mr. Obamas former pastor, the Rev. Jeremiah A. Wright Jr., Mr. Ayers has become a prime exhibit in the effort by Mr. Obamas presidential rivals to highlight what could be politically radioactive associations. In 2001, Mr. Ayers said he did not regret the Weatherman bombings. Even so, in Hyde Park, he and his wife were viewed favorably for their work in addressing city problems. Mr. Ayers was just a guy who lives in my neighborhood, Mr. Obama said recently.
The two men were involved in efforts to reform the citys education system. They appeared together on academic panels, including one organized by Michelle Obama to discuss the juvenile justice system, an area of mutual concern. Mr. Ayerss book on the subject won a rave review in The Chicago Tribune by Mr. Obama, who called it a searing and timely account.