From the Volokh Conspiracy:

It's not that surprising that he wouldn't find Ayers and Wright objectionable company--in the very liberal, Hyde Park/Ivy League circles that he's traveled in since attending Columbia, people with such views are more mainstream than, say, the average conservative evangelical Christian. That itself makes Obama far more liberal than the image his campaign attempts to portray. But what is interesting to me is that not only did Obama not personally find anything especially obnoxious about Wright's radicalism, anti-Americanism, ties to Farrakahn, and so on, or Ayers' lack of regret for his terrorist past, he apparently didn't expect that much of anyone else would care, either. How else do you explain why he didn't jettison these individuals from his life before they could damage his presidential ambitions? How else do you explain how his campaign seemed to be caught flatfooted when Obama's ties to Wright and then Ayers became campaign issues? . . .

In short, Obama's ties to Ayers and Wright suggest to me NOT that Obama agrees with their views, but that he is the product of a particular intellectual culture that finds the likes of Wright and Ayers to be no more objectionable, and likely less so, than the likes of Tom Coburn, or, perhaps, a Rush Limbaugh. Not only that, but he has been in his particular intellectual bubble so long that he was unable to recognize just how offensive the views of a Wright are to mainstream America, or how his ties to Ayers would play with the public, especially post-9/11.