Just to add to Josh's perceptive thoughts below, the weirdest thing about the media coverage tonight (particularly CNN's) is that they are discussing the race as if it's not a zero-sum game (i.e. as if Obama or Clinton does not in fact have to win). So, for instance, I keep hearing that Obama "has to" cut into Clinton's base. Huh? Clinton is not cutting into Obama's base, and if he does not cut into hers, he still wins! Josh used the word "illegitimate" to describe how much of the press would define a win that simply included the same old coalition that Obama has had since Iowa, but it's more than that. A casual viewer would honestly be led to believe that Obama can't win without a majority of old white men.
You see the result of this in the exit poll that asked which candidate would win the nomination; 43% of voters thought Hillary Clinton would. Some of this might be enthusiasm for Senator Clinton from her supporters, but it's also, um, crazy.