In an article that's mostly about the current advertising situation in late night TV (the anecdotal advertising info I tend to completely discount, public advertising information like this is hard draw conclusions from), comes some season to date comparisons for NBC's late night ratings (which we don't get from our regular sources):
O'Brien is down 22% among 18-49 viewers for the first four weeks of the season; "Late Night with Jimmy Fallon" is down 16% in 18-49 viewers
That's a big problem for NBC. A very big problem. Summer results I was willing to overlook, but the early fall trend spells disaster for NBC.
I continue to maintain that the problem with the Tonight Show ratings isn't that Jay Leno's at 10pm, it's that he's not at 11:30pm. Conan has allowed Letterman to completely close the gap with the Tonight Show and while anything can happen in the future, the current situation after 11:30 is a bad one for NBC.