Andrew Gelman has great charts breaking down how did white people vote in the 2008 election. He gives the overall election maps based on income categories. When glancing over it I focued on my home state of Maryland and the results surprised me a bit.
When voters of all races were included, Maryland was consistently a blue state regardless of income level. However, when you're talking about just whites, we're consistently red except for the <$20k and $20k-$40k income groups. This is about the same pattern as Pennsylvania and NJ, but New England tends to be much more solidly blue.
Considering that Montgomery County is a huge funding base for the Democractic party, I would have figured that even upper-income whites would have tended that way. Seems I was wrong.
Obviously 2008 Presidential elections results are not the most detailed way at looking at a state's politics. Maryland was always in the bag for Obama but he put some work into Pennsylvania. However, my quick take away is that a lot of Maryland's liberalness should be ascribed to its diversity and not cross-racial liberalness.