Glenn Greenwald has some things to say about Mayor Bloomberg:
...this is just exactly what our country desperately needs, what it is missing most -- a neoconservative, combat-avoiding, Bush-supporting, Middle-East-warmonger who sees U.S. and Israeli interests as indistinguishable and inextricably linked, with a fetish for ever-increasing government control and surveillance, and a background as a Wall St. billionaire. We just haven't had enough of those in our political culture. Our political system, more than anything, is missing the influence of people like that. That's why it's broken: not enough of those.
My view is more basic:
1) A third party candidate can't win, no matter how much money is spent. Even if he were to beat the odds and win more popular votes than Perot in 1992, the electoral college is specifically designed to crush third parties.
2) Unlike Perot who ran as a populist/conservative and took votes away from President Bush 41, the perception of Mayor Bloomberg, despite what Greenwald is saying, is that he leans more progressive. Therefore, he would obviously take more votes away from the Democratic candidate than he would the GOP candidate. That means greater odds for a President McCain or President Giuliani or President Romney Unit.