One of the more popular theories on Hillary's win is something called the "Bradley effect," which is shorthand for disguised racism. It's named for Los Angeles Mayor Tom Bradley, who in 1982 was well ahead in the polls, but ended up surprisingly losing the gubernatorial election.
Were New Hampshire residents telling pollsters what they wanted to hear, trying not to appear racist, and then switching to Clinton in the polling booth? It seems unlikely.
As pollster.com shows, Obama's 36 percent was almost exactly what aggregate polls predicted him to get. People didn't appear to leave him. As I pointed out last night, it was Clinton's numbers that were outside the margin of error; she gained an amazing nine points.
There is almost certainly no one answer for why this happened, but right now I'm not buying the racism argument, especially when the 37-24 gap Clinton worked up among women is staring us baldly in the face.
One other thought: Dick Morris famously has insisted that in most elections, undecided voters will overwhelmingly break for the challenger at the end. If in fact many primary voters resisted Obama's coronation, then perhaps his being the clear front-runner, if only for a few days, pushed that effect Clinton's way.