These people I think are fairly certain to run...
John Edwards
Hillary Clinton
Joe Biden
George Pataki
Bill Frist
Mitt Romney
If Pataki runs for either Govenor again or Senator he won't run. Its not exactly a good policy to run for President after getting crushed for office in your own state. Even if Pataki runs, he has no chance at the primary for the same reason as Rudy too socially liberal for the national GOP.
i would add Bayj to the Dems list, pretty sure he will run