Authors are treated to a fairly straight conversation with Mr. Stewart, but Stephen Colbert, who remains in character as a Bill O’Reilly-type commentator, can be a more challenging interviewer who forces the author to play along with his schtick. “It’s a different experience,” Ms. Weinberg said wryly.

Television programs that devote significant attention to serious authors have practically gone the way of the illuminated manuscript, publishers lament. Brian Lamb’s long-running “Booknotes” program on C-Span was permanently shuttered in 2004. “The Charlie Rose Show” doesn’t generate as much buzz as it used to or translate into higher sales after an author appearance, some publishers say. And the morning shows seem to prefer a bad Britney to a good book.

Many publishers shrug off “The Tonight Show With Jay Leno” on NBC and “Late Show With David Letterman” on CBS, saying they are too celebrity-driven to be interested in serious authors, and usually fail to generate a bump in sales anyway.

All that’s left are programs like “60 Minutes” on CBS, “Imus in the Morning” on MSNBC, “Larry King Live” on CNN, and, of course, “Oprah” — all extremely competitive venues for placing an author.

“The people who have abandoned us have abandoned us,” said Martha K. Levin, the publisher of Free Press, which last fall released “In the Line of Fire,” a memoir by Gen. Pervez Musharraf, the president of Pakistan. “Particularly for nonfiction, we are so dependent on media. And television has an impact that is unparalleled.”

But the Comedy Central shows are also becoming extremely competitive for publicists placing their authors. After a “Daily Show” appearance, several publishers said, the author’s Amazon ranking rises and the daily sales figures “pop,” in industry parlance. It is not at all unusual, one book publicist said, for a title to go from a 300,000 rank to a spot in the Top 300 — not often the case after shows like “Charlie Rose.”