Bill O'Reilly appeared on the David Letterman show in what appeared to be a simple ratings move. O'Reilly went over a couple points that the troops are noble and that Cindy Sheehan calling terrorists "freedom fighters" was simply wrong. Letterman didn't seem to have much to say other than that she should be respected for having lost a son and that the Iraq war intelligence was wrong.
Letterman also took the opportunity to take a cheap shot saying that "60% of what you say is crap". O'Reilly confronted him on that and Letterman admitted that he never even watched "The O'Reilly Factor". Overall I felt it was pretty much a worthless endeavour for both and didn't produce any meaningful outcome other than each making a few statements.
You can watch the interview at The Political Teen