Josh's post below raises the interesting question of whether Obama should let the Florida delegates be seated at the convention. And, I think there is a good case to be made that he--Obama, not Josh--should.
Suppose the results from the January primary are allowed to stand. This will net Clinton 37 pledged delegates, and therefore Obama's pledged delegate lead will go from approximately 161 to 124. Now, even with this hit and a big loss in Pennsylvania, it seems unlikely that Senator Clinton can get within 100 pledged delegates of Obama (the popular vote, too, looks like a long shot for her). In this scenario I see almost no chance of Clinton getting the nomination.
But, what if there is a Florida revote in June? Clinton will probably win but only net, say, half as many delegates. But she will have won another big state, not to mention the last big contest heading into the convention. Is that talking point worth twenty delegates? I think it might be. Admittedly, it's also unlikely that Clinton can win the nomination under this scenario, but it could be more likely. Clinton needs a game-changer, and a Florida re-vote in June might be the ticket. Again, I am not saying this is necessarily the case, but if I were Obama I might rather go into the convention with a 110 delegate lead and Florida a distant memory than with a 130 delegate lead and a slew of bad headlines.