Gelman's graph shows CNN's exit poll data, broken down by income and ethnicity. The green line is 2000; the purple line is 2004.
If you want more details about these graphs, his 2004 graphs exactly parallels the one I showed in my last post, but the 2000 graphs lump everyone making over $100k into one income category.
Random observation: The Hispanic voting data seem to support my pet theory that the smart long-run strategy for Republicans is to embrace Latin American immigration. Mid-income Hispanics already vote Republican. If you're willing to generalize from cross-section to time series, it's quite plausible that economic growth will gradually Republicanize Hispanics - unless anti-foreign populism gets in the way. As I suspect it will.