What happened?

I don't really know. My guess is that Republican leaders promised a certain number of votes, and failed to deliver. When it looked like the bill might not pass, a bunch of Dems who had planned to vote yea jumped ship. Right now, Republicans are trying (extremely lamely) to lay this at Pelosi's feet, for using partisan rhetoric on the floor. But whatever the reason: Epic Bailout Fail.

Silver linings: Democrats can start from scratch, write a partisan bill, get all their members aboard, and muscle it through. The fallout we're seeing on Wall Street right now will only help them. Also, I don't see how John McCain--widely perceived to have stoked House Republicans into opposing the plan--escapes a huge share of blame for this. He waffled badly during the debate and yet his fingerprints are all over today's vote.

Perhaps Republicans saw this as an opportunity to gain some leverage in the negotiations over whatever package moves forward next. But that's stupid, right? After all, how do they hope to be taken seriously when, after a steep drop in the Dow and a credit freeze, a much more united Democratic caucus can say "you killed this bill and look what happened!"