Great Map. My one question is how come there is so much red in Wisconsin while Minnesota seems far more blue. Western Wisconsin is pretty rural and white so it seems odds it went so strongly for Obama. New England is also went heavily for Obama, but this region has always been quite liberal compared to elsewhere in the US. As for Pennsylvania, no surprise, it is quite polarized between the urban and rural areas. Even New York seems to have a fair bit of blue, although looking at the county by county results it seems most counties that voted for McCain only went for him narrowly, while New York City went massively for Obama, so there was no way McCain was going to overcome Obama's strength in New York City unless he got somewhere in the neighbourhood of 2/3 of the vote in upstate New York.
Western Wisconsin was LaFolette's old electoral base, it's quite progressive while eastern Wisconsin voted for McCarthy in that (in)famous primary.
Minnesota suburbia is still hard-core Republican, and didn't switch Democrat as much in 2008 as other areas did.