A joke is a sometime thing, as wide as a church door or as delicate as a rose. The right or wrong word, too many or too few, their placement or emphasis can determine whether it's a total dud or fall down funny; the difference, as Mark Twain said, between the lightning bug and lightning.

Too much explanation or thought can whip a joke to death, so it was with trepidation that I went down to Washington last week with some fellow members of the Writers Guild of America, East, the union of which I'm president. I moderated a panel discussion of writers from The Daily Show with Jon Stewart, The Colbert Report and Late Show with David Letterman, among others, to discuss news and late night comedy.

The driving impulse for all of this was the White House Correspondents' Dinner last weekend, "The Nerd Prom," as it's become known, when inside-the-Beltway journalists and their chummy government sources cement their unholy alliance over rillettes and risotto. Over the last few years it has become an Oscar-like event, with Hollywood migrating east to hobnob with the stars of politics and commentary, distracting each other into a trivial frenzy. And you wonder why we can't get universal health care passed.

Toward the end of our strike last year, the Guild presented a successful event on Capitol Hill, a mock debate in which a team of Daily Show writers representing the Guild went up against a Colbert team posing as the studios and networks. Former White House Press Secretary Dee Dee Myers moderated. Hilarity and mirth ensued.

This time we thought we'd hitch a ride on the hoopla around the Correspondents' Dinner and succeeded. A crowd of several hundred showed up at the Newseum on Pennsylvania Avenue. The Huffington Post streamed live video and C-SPAN, which hadn't covered anything as funny since the last hearings on horticulture and organic food safety standards, videotaped the whole thing.

Not that you saw all of it. Parts of an hour of stand-up comedy by Guild writers apparently were deemed a little too raunchy for the followers of Brian Lamb and so when telecast, C-SPAN cut right to the chase -- our panel discussion.

People have been making jokes about the news and having an impact on it since the Greek playwright Aristophanes cracked wise about Socrates. Now, the late night shows are affecting traditional journalism and mainstream coverage of events, and influencing public opinion, more than ever, whether it's John McCain dissing Letterman and appearing on Katie Couric's newscast instead, President Obama on Jay Leno, or Tina Fey imitating Sarah Palin to devastating effect on Saturday Night Live.

In March, a Rasmussen poll reported that nearly one-third of Americans under 40 say they get more of their news from Jon Stewart, Stephen Colbert and other late night comedy shows than they do from traditional sources of news. The poll also found that 39% of the public says the late night shows are making Americans more informed; 21% said they're having the opposite effect.

Recently, in The Nation magazine, media critic Eric Alterman noted that the late night programs had been responsible for three of the most important and cathartic media moments of the last decade: Jon Stewart's evisceration of confrontational talk shows posing as political dialogue when he appeared on the CNN show Crossfire in October 2004 (which many believe hastened the program's demise); Stephen Colbert's controversial speech at the correspondent's dinner three years ago (in which he attacked the White House press corps' cuddly relationship with President Bush); and Jon Stewart's recent assault on CNBC's Jim Cramer and the misleading, uncritical coverage presented by financial television news in the months leading up to the crash.

Alterman wrote, "It's a sad -- almost terrifying -- comment on the state of the American media that we have come to rely on these two funnymen to tell us the truth about our country in the same way we relied on Murrow in the '50s and Walter Cronkite in the '60s."

But as we began the panel, buzzing in my head were the sage and terrible words of the late, great New Yorker magazine essayist, E. B. White: "Analyzing humor is like dissecting a frog," he wrote. "Few people are interested and the frog dies of it."

Nonetheless, we plunged ahead. So, I asked, is late night comedy telling us a truth that news can't? Are audiences turning to you for news because you ask questions and make points the mainstream media can't or won't?

"No," said my friend Tim Carvell from The Daily Show. "On some level, I'd like to think so, but I don't think that's the case. We're dessert at the end of the news menu. I actually think people who say they're getting their news from us say that as a way of protesting what they see in the news. But I feel the media isn't a monolith; there's good media and bad. We're just off to the side of it, sitting at the back of the class making comments."

Opus Moreschi, who writes for The Colbert Report, agreed. "I think if anyone's getting the news from either of our shows then that's unfortunate. Because we're not there to provide news, we're there to provide entertainment, obviously. But it may be that people who see something on our show and want to learn more find their own news sources and make up their minds. That to me is a pleasant side effect of having comedy that informs. But if all they've got is our punchline, they may walk away thinking Denny Hastert is apparently a crossdresser and that's not accurate information... Wait, sorry, I'm being told that he is."

J.R. Havlan, a comic who writes for The Daily Show added, "I feel like comedy shows and satire, what they do is not inform so much as help people learn how to watch and decipher the news. It's not about watching us to learn what's going on but learning to see what's going on and take it with a grain of salt -- that not everything they see is the truth."

And so it went. There's lots more -- war stories, background on how the shows are put together, interesting questions from the audience. You can go to the C-SPAN website to view the whole thing.

But in the end, for all the analysis and commentary that have been written about the late night shows, the bottom line remains: it's all about the funny.

By the way, we didn't actually attend the White House Correspondents' Dinner the next night, but did go to one of the after-parties at the Corcoran Galley of Art, mobbed with more than 600 guests and roaring with music at an ear-splitting pitch. We met a berobed Arabian prince who had two of the most formidable body guards I'd ever seen, big and impassive, like the statues on Easter Island.

Then we were straight-armed aside by an even larger phalanx of black-suited security men. Who's coming through, we wondered -- a cabinet member, Joe Biden, the President?

No, it was Eva Longoria, the diminutive but self-important star of Desperate Housewives.

Now that's funny.