Okay, I have definitive word on the David Letterman Obama/Edwards Top 10 list from the definitive Brent Baker of the Media Research Center:

As to how you got e-mails saying they saw the list on the show: No, they saw the YouTube video. We have the show on DVR, and the list DID NOT air. But the “Late Show” site had video of it up for about 48 hours.

So to recap: The Top 10 list was part of the program Letterman taped on July 29. It was cut from the program that aired on CBS — for time reasons, according to a spokeswoman. But the list, in text and video form, was posted on the “Late Show” website for a good while, from which people posted it on YouTube. It was taken from the “Late Show” website, according to the spokeswoman, when the CBS web types got word that it did not actually air. So it appears CBS did not axe the list for any political reasons.