Hillary Clinton has been planning to run for president for quite some time. Everybody knew when she first ran for Senate that it was a prelude to a presidential run, and everybody knew back in 2004 that she was planning to run in 2008.
In order to do that, it was essential that John Kerry lose in 2004, because she needed 4 more years of Bush, 4 more years of troops dying in Iraq, 4 more years of damage so that her campaign would be a cakewalk, just like her Senate campaign.
That's why she didn't plan to go beyond super Tuesday. She did not anticipate Obama and expected an easy nomination followed by an easy general election win.
Here is the video of Hillary Clinton on John Kerry's "botched joke". (Remember that? Notice the contrast between her comments and John McCain's). This would not be the first time Hillary Clinton has betrayed a fellow Democrat for her own personal gain.
Hillary Clinton is also well aware of the mathematics. Despite my bias, I don't think Hillary Clinton is stupid. She knows she can't really win the nomination. The chances of the superdelegates overriding the pledged delegates are next to zero. Why in the world would she force this process all the way to the convention? What other reason than to destroy Obama enough so that she may run again in 2012 against John McCain?
Given her past history, one easily connects the dots to her recent history, in which she
says McCain would be better qualified than Obama. Let's also not forget that Hillary Clinton has described John McCain as a close friend on more than one occasion. I just think her actions, past and present, speak for themselves.