Max Blumenthal over at pollster.com:
Following the 2004 election, when partial and misleading results leaked out at mid day, the network consortium that conducts the exit polls decided to restrict access to a small number of analysts in a “quarantine room” for most of the day. During the primaries this year, and presumably tonight as well, they release their results and vote estimates to producers and reporters at the television networks and other subscriber organizations about about 5:00 p.m. eastern time. While some of that information will no doubt leak after 5:00 p.m, anything you see before that time claiming to be an “exit poll” is probably bogus and certainly not part of the official network exit poll apparatus (Tom Webster, an employee of Edison Research, blogged some details about life inside the quarantine room just before the Super Tuesday primaries).
And while I have your attention, let me offer some advice: Ignore leaked exit polls tonight. I know, I know. How can you ignore them? Everyone wants to know as much as possible about the outcome of this election as soon as possible. But you will do youself a favor if you ignore what leaks out before the polls close, or at least try not to jump to any conclusions about the likely outcome based on what you see. Why? First, the McCain campaign is right: Historically, the leaked exit poll results have “tended to overstate the Democratic vote,” and as I reported in March, and the early leaked results during the primaries tended to overstate the Obama vote as well.
Does that information help? Can we apply our own informal adjustment (Obama minus some percentage) and get an precise result? Maybe, but I would not advise it.