Well, here's one where Bloomberg doesn't win any states, lol. In fact, here's two.
Scenario 1: a majority of Americans grow to like Obama, respond well to his message of change. Bloomberg, however, draws some liberal votes away from him, but he still wins narrowly.
Scenario 2: Obama falls flat on his face during the debates, making him look like the too inexperienced senator that he is, fumbling over questions like another 9-11 attack, going into Pakistan The American people trust McCain in dealing with the foreign policy issues at hand. McCain wins by a little.