I read this comment in Instapundit - Kevin Green thinks Caroline Kennedy will be the Obama VP.
This would be HUGELY popular with the Baby Boomer demographic, who still hold Kennedy in high esteem. It MIGHT pacify the Hillary crowd, although I wouldn't bet on it. If announced early enough, it might just take the wind out of Hillary's sails, leaving her no option but to graciously applaud the choice.
As a side benefit, Caroline is one of the few choices who would make Obama look experienced, by comparison.