Once the debate began on the House floor, one Republican went off on a rant about how it's all just a hoax, and got applause from his fellow conservatives. So it's nice to see that there's a good intellectual dialogue going on already.
Al Gore wrote a blog entry on the bill, saying "there is no back-up plan". I think he's exactly right. If we don't pass this bill, there's nothing in the wings. We won't pass carbon legislation for years, and we'll go into the Copenhagen negotiations in December with nothing to add. What's the point in agreeing to carbon emissions reductions when you can't get the related legislation passed? China will have little motivation to reduce their emissions when we continue to fail to regulate ours. To be blunt, I think if this bill doesn't pass, it will be a disaster.
A good gauge will be the margin by which it passes in the House (assuming it passes, which it should). If the Democrats can hold most of their moderates and get a few Republicans on board, it bodes well for passage in the Senate. If it only passes by a slim margin, the road through the Senate will be extremely difficult. No doubt they'll hold off on bringing it to the Senate floor until the climate (no pun intended) is more favorable (i.e. higher gas prices, stronger economy, better approval for Obama).
Pelosi has said she wants a vote on the bill in the House before the 4th of July break. You can see a list of undecided congressmen here.