Rob brought this issue up in the comments to last night's convention post, but the traffic has likely shifted from there and the roll call is certainly worth its own place. Here are a few things I've been able to dig up regarding the process.
1) DemConWatch has it that the floor vote will be a truncated affair. The voting will take place beforehand.
2) In fact, jack-of-all-trades, Seth Masket, who is a delegate, a blogger and a political scientist confirms that the Colorado delegation voted this morning at the delegation breakfast.
What we'll see tonight is a part of the deal hammered out between the Clinton and Obama teams. We'll get a limited number of states announcing their results and then they'll move on. I'd guess the New York delegation plays a prominent role.
Regardless, the roll call will take place between 5 and 7pm ET, so C-SPAN will be where I'll be able to catch it. I don't know what the cable news outlets have been doing (gavel-to-gavel coverage?). Bill Clinton is on at 9pm and Biden follows during the latter half of the 10pm hour.
[See the full schedule of the night here.]
The Electoral College Map (8/27/08)
The Links (8/27/08)
Some Good One-Liners Tonight at the Democratic Convention