to this Rolling Stone article
about the possibility of Gore running in 2008:
If the Democrats were going to sit down and construct the perfect candidate for 2008, they'd be hard-pressed to improve on Gore. Unlike Hillary Clinton, he has no controversial vote on Iraq to defend. Unlike Barack Obama and John Edwards, he has extensive experience in both the Senate and the White House. He has put aside his wooden, policy-wonk demeanor to emerge as the Bush administration's most eloquent critic. And thanks to An Inconvenient Truth, Gore is not only the most impassioned leader on the most urgent crisis facing the planet, he's also a Hollywood celebrity, the star of the third-highest-grossing documentary of all time.
For what it's worth, I'd probably support him enthusiastically if he ran.