Let me add this as well, because this is the only actual description I've read or heard of what actually went down in the meeting. It comes from an account given by Paul Begala on Larry King just now, who obviously is a biased source, but again, it's the ONLY account out there right now:
Meeting takes place in the cabinet room of the White House. All members of the Senate Banking Committee and the House Financial Services Committee are there, along with Paulson, Speaker Pelosi, Harry Reid, House Majority Leader Steny Hoyer, House Minority Leader John A. Boehner, the aforementioned Rep. Shelby, and of course McCain and Obama (at opposite ends of the table, natch).
Bush makes a statement opening the meeting, then the press is ushered out.
It is traditional for the Speaker of the House to speak first, since she is the highest ranking person in the room after the president. Pelosi cedes the floor to Obama, who is tapped to articulate the Democratic position on the bailout.
Obama lays out the requirements he has been talking about all week that have been, by all accounts, worked into the deal (oversight, cap on CEO salaries, guarantees on return of taxpayer investment). Incidentally, these are pretty much the same things McCain claimed he wanted.
It's now the Republicans turn to speak, so Obama throws it to McCain. McCain says "I believe in traditional rules of seniority, so I'm going to defer to Sen. Boehner." MCCAIN THEN DOES NOT SPEAK FOR THE NEXT 43 MINUTES.
Boehner floats a previously unheard of plan devised by House Republicans involving private mortgage insurance and a cut in the capital gains tax.
Obama asks Boehner (or anyone else) for more details on this plan. Boehner has none and concedes they haven't even put anything on paper.
Obama asks Paulson if this alternate plan, as roughly outlined, will work.
Paulson says no way.
During this time Shelby basically says "we ain't doin' this, no way, no how," waves his precious letter around, and throws the whole meeting into chaos before walking out in a huff.
Obama at one point interrupts and directly asks McCain for his opinion since he has said nothing the entire time (after ostensibly flying up here for the sole purpose of successfully shepherding a bailout plan through). McCain hems and haws for all of two minutes, saying he might support the House Republican plan but he doesn't really know.
Everyone walks out pissed.
Way to lead, Maverick!
EDIT: Augmented with some details from the Washington Post.