Barack Obama made a comment at the South Carolina debate about not knowing which Clinton was running for President. Although it was an off-hand remark, it was an astute one. Both Bill and Hillary Clinton are working on a plan to help her win the nomination and, possibly, the Presidency.
One of Hillary's most damaging weaknesses is her inability to really connect with people. She's tried any number of tactics to make herself appear more human, such as the crying incident in New Hampshire, but it hasn't really worked so well. On the other hand, Bill has a way with people that is amazing to watch. He captivates audiences with his words and mannerisms like no other politician, living or dead. (Of course, the dead politicians have to do a lot more to captivate an audience, what with the cries of "The dead have come back to life!" and all...)
What Hillary's campaign has done is split the Clintons. One does the actual hard campaigning (Hillary), and the other does the softer touch campaigning (Bill). This strategy can be effective if done properly and if both parties remember what they're supposed to do. When there are breakdowns, like Bill yelling at reporters or lying about Obama, it throws sand in the gears of an otherwise well-oiled machine.
Right now, the focus is on the question of whether Bill helps Hillary. Clearly, he helps her because he adds an element to her campaign that isn't there without him: likability. The gaffes and the attacks on Obama sting, but don't really hurt Hillary overall because there are enough Democrats who wistfully remember Bill's two terms in office to want him back there come January 2009. And putting Bill to work to stump for Hillary is one way to do it.
But there is a caveat to this. Bill needs to stop with the attacks on Obama and focus more on what Hillary brings to the table if he wants Hillary's charm offensive to be more charm and less offensive. The more Bill shows off his angry, darker side, the bigger the risk to Hillary's campaign. A jovial Bill is good. An angry Bill is not.
We'll see if Hillary's two-prong campaign approach will earn her the nomination, but I'm betting it will. And then, Hillary will get crushed in the general election, so it all works out in the end.