Giuliani is hardly contesting New Hampshire. He's not fighting for Michigan. He won't show in South Carolina.
He's crazy. Crazy like a fox: Romney came out of Iowa in worse shape from his 2nd place finish than did McCain (4th) or Giuliani (6th). Similarly, McCain and Romney (and even Huckabee, for different reasons) have a lot at stake in New Hampshire. Giuliani can come in behind Ron Paul again and not compromise his campaign.
The G.O.P. campaign seems like it's shaping up as a tournament; or at least a series of one-on-one contests. Iowa was Huckabee v. Romney; New Hampshire is Romney v. McCain. The latter two will rematch in Michigan. South Carolina could end up being Thompson v. Huckabee, particularly if Michigan and New Hampshire split. A candidate can be knocked out only in primaries he contests.
Giuliani, therefore, earns the equivalent of a first-round bye. In Florida, he'll be pitted against whomever has emerged from the previous contests. It could be three-way: the winner of Huckabee-Thompson, the winner of Romney-McCain, and Hizzoner. But I'm guessing that a clear front-runner will emerge after South Carolina - Huckabee if he runs away with the state, the winner of McCain-Romney otherwise, and this frontrunner will challenge Giuliani.
Thus, in the spirit of creating an NCAA Division 1A football playoff, add to the list of proposed presidential primary reforms a sporting alternative: candidate playoffs. Seriously, this could work.