If you care about this, again, you've probably already heard it, but

It's official: Bush supporters are, speaking broadly, ignorant or stupid.

Lots of sources for this, but here are two good ones: Dana Milbank in The Washington Post

On al Qaeda's ties to Iraq, similarly, 75 percent of Bush supporters believed that Iraq either gave al Qaeda "substantial support" or direct involvement in the Sept. 11, 2001, attacks; 30 percent of Kerry supporters held these views. A majority of Bush supporters believed the 9/11 commission backed them up on these beliefs, although the panel found no cooperation between the two, only some contacts.

and The Poor Man, "Cluebags for Bush":

Combined with last year's study of how partisan media viewership and politics influences the public's understanding of very basic facts about the world, we can reach but one conclusion: while you don't have to be a clueless FOX News moron to support Bush, it sure helps.

And a picture is worth a thousand individual facts: