This isn't what you'd call "surprising" news.
Specter was mildly caught between a rock and a hard place. He could either vote against WH policies, and thus risk very likely being vote out of office by his moderate constituents next year; or he could vote for WH policies, and then have the GOP throw its support behind Pat Toomey; or I suppose he could try to burn the candle at both ends, which I presume wasn't working very well for him.
I can't say this makes him look very good, not a month after vowing to run again as a Republican on a Republican ticket. If you have opinions and values, then stick up for them. I have a hard time seeing this as anything other than a move to assure he gets re-elected in 2010.
My friend Kevin, who hails from the other side of the aisle from me, to be delicate, put it a little more piquantly: "The guy is a narcissistic douchebag, pure and simple."
Hard to argue with that. The guy just basically crapped all over his political history for the sake of getting re-elected in 2010. That was no certain thing anyway -- Pennsylvania has been trending more and more moderately of late, and he was no sure thing against whomever the Democrats threw at him next year. And he was facing a hard fight against Pat Toomey anyway.
I'm tempted to rhetorically wonder if the Dems really want someone like this in their ranks, but I'm sure they'll hold their nose and be pleased as punch with their supermajority once Franken takes his seat. The Republics would do a similar nose-hold/embrace were the situation reversed.
Ahh, politics. That sausage-factory tour is looking better and better, isn't it?