A cool visual interpretation (click to enlarge) of what McCain would have to do to win the election. This is why people have been saying now for a while that Colorado is going to be the tipping point. Nate Silver wrote a month ago:
Colorado remains the best bet; it’s projecting eight-tenths of a point better than Obama’s national numbers. What that means is that, theoretically at least, Obama would still be expected to have a winning elecotral map if he lost the popular vote by 0.8 points. That is why Colorado is so essential; it is the state most likely to be involved in a split result between the popular vote and the Electoral College.