So Specter told a pro labor crowd that "...you'll be satisfied with my vote on this issue" (video here). This was probably inevitable. The really key issue here is that this race is almost certainly Specter's last. And, now that he's a Dem (that will almost certainly enjoy significant Independent and Republican support), there's simply more to be gained by supporting EFCA than opposing it. Is be burning 30 years worth of bridges with previous supporters? Yup. Does he give a damn? Nope.
You've almost got to admire his complete lack of personal conviction. You suspect it out of a lot of politicians, but Specter doesn't even try to pull the wool over your eyes. I remember on Meet the Press, after he switched parties, when David Gregory asked him why, and he explicitly said it was because it looked like he might lose the Republican primary.
I don't much care for Specter's politics, and I'm poking fun at him, but truthfully there are worse philosophies by which to govern (advocate for what your constituents want/need -- a true adherer to the delegate model of governance for you PolSci dorks out there).
This does beg the question of why in the world he explicitly stated, in the statement in which he switched parties, that he would continue to oppose EFCA. It makes him look like an unprincipled fraud, and will provide ammunition for more than a few 30 second TV spots by his Republican opponent.