Somehow, YouTube already has a copy of David Letterman tonight lacerating John McCain for skipping the Late Show and suspending his campaign in the midst of the Wall Street meltdown. As reported earlier by Drudge, Letterman became especially upset when he caught the Republican presidential nominee in a live feed from New York being interviewed by his own network's Katie Couric. McCain had personally told Letterman he was canceling because he was headed back to the capital to handle the financial crisis. Whoops.

Letterman invited lefty MSNBC anchor Keith Olbermann to fill for McCain and spent huge stretches of his broadcast laying into the candidate, saying he was acting "fishy" by not letting his running mate Sarah Palin take over the campaign.

It remains a mystery how this ended up on YouTube. Did someone at Letterman leak it? Why, and why not wait until after the broadcast airs? Do show producers fear CBS suits will quash the broadcast for its heavy political overtones? Or did they think they risked a ratings disaster without their A-list guest and were hoping to either effectively tease the McCain-less show or maximize revenge against the McCain camp?

Whether they capitalize on it financially or otherwise, Late Show producers have created some fascinating television. Watch the most incendiary two minutes and forty five seconds in the video above or click through for the full nine minute compilation on YouTube, via Cajun Boy.