Could be, according to this Politico article. The focus is on VA gov Tim Kaine, but the others mentioned are Bayh, Sebelius, and Biden.
If that is the case, I say it will be Biden. Bayh is at least a risk of losing a senate seat, which could prove to be the difference between 59 and 60, or 60 and 61. Sebelius isn't going to deliver Kansas or help in any other state, and she just doesn't complement or fill-in Obama effectively. Kaine may actually prove to be a drag in VA, as his approvals are mediocre. But floating him so prominently probably helps minimally in VA if people think that he may get an prominent appointment that could somehow be beneficial to the state.
If it is ether Bayh or Biden than I will feel fulfilled in my prediction that the blogosphere would not be happy with the VP choice, and I am now highly confident it will be one of them.