While I'm indulging in wild speculation... I wonder if these combinations would work. Janet Napolitano has been mentioned as a VP or Presidential candidate for some time, and could provide additional female appeal for Obama--who is looking like the new front-runner in the Democratic race. I cannot see him picking a Washington insider, not after Iowa voted so strongly for "change"--and that rules out all remaining Democratic hopefuls, I think. On the other hand, if Hillary sticks it out and pulls off a win, Gen Wesley Clark, who endorsed Hillary months ago, would provide additional national security credentials.