Arlen Specter switches parties. Says his vote for Obama's stimulus bill created a "schism" with state Republicans that can't be fixed, and that his political philosophy is more in line with Democrats than Republicans now that the GOP has moved so far to the right.
I'm not sure actually what a difference this will make, other than his re-election will become easier, but still pretty incredible symbolically. The current Republican Party is out of touch with huge swaths of the country. They appeal to Utah and the Deep South. That's it.
If they had any sense, Senators Snowe and Collins in Maine would follow suit.