This isn't at all a phenomenon unique to this election, but it's worth pointing out, and relevant to the previous discussion of income and perceived social mobility.

From CNN's exit polls:

Household income       Obama  McCain  Other

Under $15,000 (6%)       73%    25%     2%
$15-30,000 (12%)         60%    37%     3%
$30-50,000 (19%)         55%    43%     2%
$50-75,000 (21%)         48%    49%     3%
$75-100,000 (15%)        51%    48%     1%
$100-150,000 (14%)       48%    51%     1%
$150-200,000 (6%)        48%    50%     2%
$200,000 or More (6%)    52%    46%     2%

Let's graph that:

What do you see? A local maximum for Republican voting rates. And that Obama actually won the $200k+ vote.

Again, this isn't new. Democrats traditionally do well with the highly educated, and the highly educated tend to be highly compensated. Another possible explanation: at some point, tax rates at high brackets take a back seat to other concerns, especially if you consider the fact that current top rate, 35%, and the proposed new rate, 39%, are relatively low by historical standards.

It certainly throws a wrench into the Joe the Plumber storyline.

(Sorry, I've been sitting on that pun for a while.)