David Letterman has decided to step into the NBC fray with a relentless attack on Tuesday, that ripped Jay Leno as a "phony". David Letterman also seemed to offer some support for Conan O'Brien as well. Letterman was responding to Leno's famous "Don't blame Conan" statement from Monday evening. Letterman was critical that Leno didn't move on to some other network after leaving THE TONIGHT SHOW as well.
Letterman's LATE SHOW even ran a fake TONIGHT SHOW ad that took aim at Leno as well. But probably, a large part of Letterman's wrath is his continued anger at not getting THE TONIGHT SHOW helm years ago when NBC handed it off to Jay Leno from Johnny Carson. David Letterman was Johnny Carson's choice as well, but NBC executives chose Leno over his objections.
However, Letterman didn't really address the simple economics at hand for NBC. NBC would have lost an estimated $3-5 in 2010 with Conan, but can make a $25-40 million profit with Jay Leno at THE TONIGHT SHOW helm.