While they appear to be running neck-and-neck on the chart on the link below, Leno's "Tonight Show" holds a lead over Letterman's "Late Show" by at least 1 million viewers (adults 18-49).
http://tvbythenumbers.com/2010/04/15/jay-lenos-tonight-show-6-ratings-wins-in-6-weeks/48695
It appears Letterman's share fluctuates between 900,000 viewers and 1 million on any given week. However, Leno has shown no gains since his return to 11:35 PM last month. A week in which Letterman has all new shows while Leno presents reruns could be the game changer in this race.
http://tvbythenumbers.com/2010/04/15/jay-lenos-tonight-show-6-ratings-wins-in-6-weeks/48695
It appears Letterman's share fluctuates between 900,000 viewers and 1 million on any given week. However, Leno has shown no gains since his return to 11:35 PM last month. A week in which Letterman has all new shows while Leno presents reruns could be the game changer in this race.