ARTICLE: "How Big a Stretch? For Barack Obama, Winning the White House Would Mean Bridging The Biggest Gap Of All," By Lynne Duke, Washington Post, May 7, 2007; Page C01
Seriously, for me, the attraction to Obama is: 1) generational, and 2) a sense of competency and vision.
As for the underlying question of "Is white America evolved enough to elect a black man president?" I find that sentence alone weirdly racial. Obama's half black and half white, so continuing to view him as "limited" somehow politically by his blackness seems so last century (the queer "one drop" rule).
If you want to go that route and make such arguments, then try this one on for size: Obama's the first black who's seriously qualified for the job. No one who ran before could be viewed so, either because the appeal was limited (Jordan was never believable, like electing your stern, lecturing aunt), the platform too narrow (Chisolm simply had no national standing, a la Kucinich she was a fanciful symbol), the candidate too weird (Jackson was and remains a Perot-like egomaniac without enough reliability) or the character too questionable (Brown was always the accidental candidate who lucked out).
Obama's serious because he covers all the bases, like any credible candidate does: great platform, great message, great appeal, great delivery, seems competent--the whole nine yards. His problem is that Hillary hits on all cylinders too, which makes the generational appeal perhaps the differential.
But I stick to some doubts on him, in that I still see him as JFK '56 and not quite yet JFK '60, so I think he'll run as Veep, like Kennedy almost did in 1956.