I caught some Fox News tonight and, between O'Reilly and Hannity, saw that New Yorker Obama cover flashed about ten times. (MSNBC was also all over this story all day, including a segment in which I was a guest, which was sandwiched between two other segments touching on the same topic.)
The Obama campaign really helped to whip up this firestorm. A central objection to the cover is that people who don't read or "get" the New Yorker will see the cartoon and somehow take it seriously, reinforcing noxious myths about Barack and Michelle.
Well, had Obama simply shrugged it off, instead of having his spokesman brand the image "tasteless and offensive," I don't think this story would have blown up so dramatically. It's the man-bites-dog conflict, the internecine liberal feud, that makes it so sexy to the media--and particularly an outlet like Fox. No tart comment from the Obama camp, no breathless daylong exposure (or far less of it, at least.) I'd say that by denouncing the cartoon the Obama campaign magnified the reach of that image tenfold.
Update: In a post I'd missed, Isaac predicted the Obama response would have this effect.