As Death said, it's not a surprise, since he has campaigned with McCain since the beginning. Unlike Zell, however, Joe is still very much a democrat, so he'll probably serve as a character witness and show the general public that it's ok to support someone that that doesn't share your ideology if you think they are the most qualified and capable.
He was kicked out of the Democratic party back in August of 2006, which must have been a very personal and humiliating experience for him. I'm not sure whether to blame the activists for alienating him so profoundly or give them credit for seeing into his character earlier than others.
