Obama's pushing back pretty hard on Hillary Clinton's claims of experience. "There is no doubt that Bill Clinton had faith in her and consulted with her on issues, in the same way that I would consult with Michelle, if there were issues," said Obama. "On the other had, I don't think Michelle would claim that she is the best qualified person to be a United States Senator by virtue of me talking to her on occasion about the work I've done."
Clinton's really opened herself up for this attack -- I'm actually surprised it took Obama so long to get around to it. Clinton herself hasn't defined the terms of her experience, in part because it's probably impossible to do. If Obama can define it, and thus her, as "being Bill Clinton's wife," that's going to have a tremendous impact on the campaign, and only in part because it will impinge on her "experience" narrative.
Politics of it aside, the actual epistemological issues here are tricky. Hillary Clinton clearly has no experience being President of the United States. Nor does Obama, or Edwards, or Romney, or Paul. Their experience at being President is precisely equivalent to mine. So what we're really talking about is who has the most relevant knowledge about being president. And here are, basically, our options: