It's going to be a long night. Greg Sargent has confirmed with Sarah Binder, an expert in governance studies at Brookings Institution that Reid's parliamentary procedure on this is solid.

She points to this particular Senate reg: Whenever upon such roll call it shall be ascertained that a quorum is not present, a majority of the Senators present may direct the Sergeant at Arms to request, and, when necessary, to compel the attendance of the absent Senators... And yes, this has apparently happened before, in 1988, when Majority Leader Robert Byrd, D-W.Va., ordered round-the-clock Senate sessions that were boycotted by Republicans. Charlie Cook recounts that Byrd ordered the Senate's sergeant-at-arms to arrest absent senators and bring them to the floor. Capitol cops arrested Sen. Robert Packwood, R-Ore., and even removed him from a locked Senate office and carried him onto the Senate floor, Cook writes.

(If I remember correctly, Packwood wasn't just hiding in his office, but in the bathroom in his office. But my memory could be faulty. It makes a good story, anyway.)

At any rate, the night is going to be long. Howard Dean says (in e-mail):

Now, let's not kid ourselves: they can filibuster, and we probably won't have the votes to stop them. But if Senate Republicans are against ending the war, then they should show it by voting against the legislation -- a straight-up-and-down vote on a bill that the majority of Americans support. That's how a democratic government works. Instead, they're threatening to block the vote, and we're going to force them to explain themselves in front of the American people. So let's show Senator Reid that we're united behind him. We've created a simple tool that will let you write a letter and fax it to your Senators instantly -- you can let them know all night long just how much opposition there is to the war in Iraq. Send your Senators a message right now: http://www.democrats.org/....

Let your Senators know you're hanging out with them tonight. Give their staff who have to stay, too, some company and something to do tonight. And let them know one simple thing. We want our troops to come home.