Actually, along with the bombings, Ayers and his wife are suspected of having supplied guns for a bank robbery that got a police officer killed in 1974. It might have gone to court if the investigation by the Nixon-era justice department and the barely post-Hoover FBI had been so riddled with violations of the law and such that any conviction of Ayers and his wife would have been tossed out on appeal.
As for Ayer's now-respectable position, it was purchased for him by his father, who spread around enough money to the right institutions to allow sonny-boy to slink back into The Establishment while still pretending to be a Daring Revolutionary.
But very little of this has anything to do with Obama. As many have noted, Obama was eight years old and living in Hawaii when Ayers and Dohrn were planting bombs and other such useless activities (it wasn't The Weather Underground that got us out of Vietnam, it was the disgust of Nixon's Silent Majority at sending their kids as cannon fodder that did so--Nixon bought the silence of the campus "radicals" by making grad students ineligible for the draft shortly after the Kent State riots ended with four kids shot). As best as I can tell, his actual relationship consisted of serving on the board of an education charity run by Walter Annenberg, about as right-wing a Republican as you can get, and the one fund-raiser that Ayers held for Obama at the beginning of his political career. (has anyone considered that Ayers was trying to latch on to Obama and claim bragging rights as his mentor? Is so, it hasn't worked.)
Was there more of a political or personal relationship? If so, I haven't seen the proof. But if there was, and Obama manipulated this putz into helping move his career ahead, good for Obama. It's probably the only useful thing Ayers has ever done . . .