These state-by-state scatterplots show the regional distribution of the Obama vote in 2008 versus the Kerry vote in 2004, and the Kerry vote versus the Gore vote in 2000. The states above (left of) the 45-degree diagonal line are those that went Democratic. The plots look pretty similar, huh? To be precise, the standard deviation between 2008-2004 was 3%, and the 2004-2000 SD was only 2.4%, so the electoral map has not changed much since 2000 apart from the obvious outlier of Hawaii (favorite son effect).
The plots come from a blog called Red State, Blue State, Rich State, Poor State, which is written by a group of professors in political science and statistics departments. They have highly satisfying stuff if you like your election analysis quantified and on the dry side.