When Stephen Colbert was a guest on "Late Night with David Letterman" in October, he tweaked the show's host.
"We're on right now, we're opposite you right now," said Colbert, whose "Colbert Report" on Comedy Central airs at the same time as Letterman's show. "I'm actually telling my audience to watch me on this show."
Letterman responded, "I appreciate it. [We'll] take all the help we can get."
Maybe the longtime late-night host, who just signed a $35 million-a-year deal to stay on the air until 2010, was reading the tea leaves when it comes to his own ratings.
Letterman's audience, along with that of rival "Tonight Show with Jay Leno," has declined, as the Nielsen ratings for both shows slipped 6 percent compared with a year ago, according to Media Life trade magazine.
And Colbert has every reason to feel generous about his audience. The number of households watching "The Colbert Report" and John Stewart's "Daily Show," the news block of Comedy Central's late-night lineup, have increased almost 7 percent compared with a year ago, according to Nielsen.
And it's not just fake news that's attracting viewers. "Nightline," which is devoted to serious reportage, also added viewers, as ratings grew 4 percent compared with last year.
Overall, the audiences for the late-night legends still dwarf the news programs. At 4.4 million, Leno attracts almost four times as many viewers as Stewart.
But expect the current trends to continue. "You have a new generation of viewers looking for alternatives," says Marc Berman, senior editor at MediaWeek.
"Leno's been on for over a decade, and people are getting to a point where they're tired. It will continue to decline. The erosion for Leno and Letterman will continue since their audience is aging."
Current events are also driving more viewers to tune in to news, both fake and real. "It's an election year, and the war in Iraq is dominating headlines, so it's natural that you have people tuning in to news," says Kathleen Hall Jamieson, director of the Annenberg Public Policy Center at the University of Pennsylvania.
She cautions that some of the ratings changes are due to the intensity of the current news cycle and may not reflect permanent changes in viewing habits. "You want to see how the numbers are when politics is out of the news."
But John Rash, director of broadcast negotiations at Campbell Mithun Advertising, believes there is a broader transformation at work in which viewers are less interested in seeing their hosts trade jokes with celebrity guests.
"Late-night shows are further removed from the daily discourse," says Rash. "The new generation grew up comfortably embracing irony and the way that Comedy Central is able to pierce the public consciousness, it's more like a new form of political and cultural entertainment."
And tastes will continue to skew in that direction. "Look at Borat -- he's a much more aggressive version of "The Colbert Report," says Rash. "The envelope will be pushed even further."