Here's an article by Bill Carter on the relative ratings of Leno and Letterman. This one should be read the way you read any political report, with the spokesperson for each side madly spinning their weaknesses as strengths and blaming others for their own shortcomings. And keep in mind that neither show is in any jeopardy of being cancelled. This is, for the folks who put the shows together, all about ego. And for the networks, it's all about trying to make profitable shows even more profitable.