Data geeks, start your search engines (American Factfinder). The U.S. Census Bureau has just released 2008-2010 American Community Survey estimates--the best source for socioeconomic information. The three-year estimates are available for the U.S., all 50 states (plus the District of Columbia and Puerto Rico), congressional districts, Metropolitan Statistical Areas, and counties/places with populations of 20,000 or more.
You can access the data via the American Factfinder.