I forget the specifics, but George Will recently mentioned the possible this nightmare scenario where the electoral college would be effectively tied and the House of Representatives would have to decide it. I don't think it would ever get that far though. The party out of power in the House (in this case, the Democrats) would seek a recount in one of the key states in such a way to bypass such a House decision. This map is really not that out of the bounds of possibilities (just a few states flipped from Kerry in 2004 and OBama in 2008 would cause it):