There are a lot of political insiders that say there should be a Hillary-Obama or Obama-Hillary ticket in order to "patch up" the rift that may have been created within the Democratic Party as a result of this "bloody" and historically long nomination process. By having a combined ticket, it is felt that any possible defections or disaffection of Democratic voters would be softened, and those Hillary supporters would come over to an Obama-Hillary ticket or vice versa.
However, my guess is that Hillary, for sure, won't buy into the V.P. slot with Obama. To understand this, you must understand what drives the Clinton's; and, what drives them isn't being second. I believe that Hillary is so P.O.'d about having to contest this race when she "thought" that she was almost entitled to the Democratic nomination that she would never, again, accept Obama on a friendly basis. After all, I am sure she stayed with Bill all these years because of the very likelihood that his association would assist her in getting to be President (Little did she know how Bill could be such a problem; rather than an asset!). Also, in the back of her mind is the fact that she might have a chance to run again if Obama loses in the Fall; just like John McCain, this time around. If she did take the V.P. slot and Obama loses against McCain, she knows she would go the way of hundreds of also-ran V.P.'s who never got another chance at the Presidency; i.e. Dan Quayle, Joe Lieberman, and John Edwards. Also, if Obama becomes a one-term President because of a failed Presidency, she knows that she would be tarnished and never be able to run again. Lastly, if Hillary actually did take the V.P. slot and Mr. Obama became a two-term President, it would be eight years before she would have a shot. In eight years, she would 70 years old. While age really shouldn't matter, it might be McCain's undoing this year and it could be Hillary's in 2016. Also, a lot can happen between now and 2016. Another recession? A scandal of some kind? Some terror attack? Another situation like those could seriously affect the Veep from getting the next Presidency; just as it happened to Al Gore in 2000.
On the Obama side, I don't think he will actually have to consider the Veep slot. That's because I don't believe Hillary will win. Also, I don't think he would offer Hillary the slot because she has so much baggage; especially, her credibility as a result of all those bogus stories. Hillary's "likeability" numbers are just terrible! But, if he had to make that decision, I think he might think Hillary is unelectable and would decline the V.P. position; thinking he would be free to run again, untarnished, in 2012.
Now, for my prediction on the Democratic V.P. pick. I think Obama will win the nomination and Hillary, for all the reasons above, won't accept the second place slot on that ticket. Besides, if he adds Hillary, he'll probably have Bill Clinton and all his baggage as part of the deal; and, that would be a mistake! Instead, I believe that Obama will decide to pick another white woman for his running mate. He will do this to try and regain any disaffected Democratic voters that might either vote for McCain or that might decide to not vote at all. This decision will be based on the concept of a "historic first" for the Democratic Party that may be unstoppable in this election. My guess is that it might be Kathleen Sebelius, the Governor of Kansas and a shining/rising star in the Democratic Party. She is certainly less tainted and more likeable than Hillary Clinton. Further, someone like Sebelius, from the heartland of America, might help Obama overcome his "clinging to guns and God" debacle.