Talking to Americans
Hillary Clinton: She's in! Under the US alternance policy, it's time for a Clinton to be President so this certainly works in Hillary's favour. She's been working hard to dull her reputation as a left wing New England liberal in recent years by going right on some social issues. With the best campaigner of this generation helping her out, she stands a very good chance to win the nomination.
Barack Obama: The potential for obamania is certainly there with this young and charismatic candidate. He's got youth, he's got a great personal story he's got charisma; what he doesn't have is a ton of political experience. Obama is young enough that he doesn't have to win to position himself for a future nomination but he certainly could ride a groundswell of support to a win.
John Edwards: I always felt Edwards would have been the most electable choice for the Democrats in 2004 and, out of the gate, I'm of mostly the same opinion for 2008.
Bill Richardson: This half-Mexican governor of New Mexico has a long political resume behind his name, although he lacks the flair of the three front-runners.
Joe Biden: He's seen as more centrist than the field, especially on foreign policy. Lost the '88 nomination to the Michael Dukakis juggernaut.
Tom Vilsack: Let the Vilsackian revolution begin!
Unlikely to Run
Al Gore: If I were living in the states and if Gore ran, I'd probably be supporting him. Although he likely won't get an endorsement from his former boss, Gore's experience as VP will serve him well with voters. And, unlike the rest of the field, he's also got experience of actually winning a Presidential election. Unfortunately, the inconvenient truth of it all is that Gore is unlike to run.
Dennis Kucinich: Can Frodo pull off a miracle? Not very likely.
Christopher Dodd: Dodd has hired a former John Kerry campaign manager to run his bid. I guess David Herle was busy.
Mike Gravel: This 75 year old candidate could be the choice if Democrats decide their best bet is to make John McCain seem too young and inexperienced for the presidency.
Oh God No!!!
UPDATE: APL has a very thorough and very good run-down of the Republican field.