There's been some talk about whether either Clinton or Obama would choose the other as VP. My thots are: Clinton would just about have to choose Obama, but Obama has no reason to choose her.
If Clinton wins, she will have very little choice but to choose Obama, for several reasons. He brings a huge number of people to the table, particularly African-Americans. That's normally a solid group for Dems, particularly for a Clinton. But the Clintons have managed to alienate their traditional allies, and healing would be good. Obama also has a superb organization that can raise a lot of money and mobilize hundreds of thousands of people. If she doesn't choose him, lots and lots and lots of people will be pissed off at her. There will probably be some white men who won't vote for a combination of a woman and a black man, but most of those people won't vote for a Democrat.
The next question is whether or not Obama would say yes. There are some theoretical/ethical reasons for him to say no. Does he really want to be part of a Clinton administration? Would it compromise his attempt to move beyond the politics of negativity to say yes to Hillary? That's a real concern. But he could also argue that his highest principle is getting a Democrat elected to office. Some people will accuse him of selling out. But I don't think we can afford to have another Republican as President. Also, if Clinton loses, he'll be in a great position to run again in four years, because people will blame Clinton for the loss, not him. It's mostly a positive for him to run with Clinton.
But Obama-Clinton? Not such a good idea. Her presence would alienate a lot of people. Obama likes to talk about "Obama Republicans," i.e. people who will cross party lines because they are sick of partisanship, and believe in his cause of finding common solutions to our problems. Like the "Reagan Democrats" of the 1980's. The potential for this kind of bipartisanship is part of why I like Obama. But if she's on the ticket, those people are history. I think Obama would do well to choose a woman as his VP, particularly a woman governor. But it's not essential for him to do so. He was raised by a single mother, he's married to a strong woman, and he has two daughters - he's very sympathetic to the concerns of women. I think he can communicate that without Hillary being part of the equation.