Bingo!
Of course, most white people who voted for Obama did so because they have liberal beliefs. But a surprising number of self-described "conservatives" and Republicans did so as well; this is the "white guilt" factor of which you speak.
Now that they've ticked the "I'm not a racist" box by voting once for Obama, and bragged to their friends about it, many will feel free to migrate back to the conservative side of the ballot in 2010 and 2012.
A good model for this phenomenon here in North Carolina is a chap by the name of Harvey Gantt, who was, as the media reminded us ceaselessly, was the first black graduate of Clemson University in South Carolina. Gantt harvested a good deal of white guilt in 1982 -- running unusually strong in upper-income white precincts in addition to his near-unanimous support among blacks -- and was elected mayor of Charlotte. The "white guilt" wore off, however, when he ran for reelection in 1986. He went on to be twice nominated for the U.S. Senate, but was defeated both times by Jesse Helms.
WooHoo!