Mayor Martin O'Malley, wife Catherine

Baltimore Mayor Martin O'Malley and his wife, Catherine, today walk outside City Hall, where the couple denounced rumors of infidelity spread by an aide to Gov. Robert L. Ehrlich Jr. (Sun photo by Christopher T. Assaf / February 9, 2005)

"I don't like O'Malley and I am no Dumbocrat / Caligulite. Still, methinks you should validate stuff like this before you post it."

So wrote "Sartorius" on Aug. 13, 2004. The participant in a discussion board on FreeRepublic.com was responding to an explosive posting that Baltimore Mayor Martin O'Malley was having an extramarital affair.

It turns out that even Web posters themselves question the publishing power the Internet grants anyone with a modem.

Sartorius's skepticism proved salient: Another person posting about the topic was revealed this week to be Joseph Steffen, a longtime political operative for O'Malley's political rival, Gov. Robert L. Ehrlich Jr.

That story, and Steffen's resignation, broke in the mainstream media. But it highlights how Web sites - with their freewheeling rumors and rants - increasingly are forcing more traditional news institutions to write articles that otherwise wouldn't see the light of day.

Rumors of O'Malley's alleged infidelity have long circulated in Baltimore but were not printed in such daily newspapers as The Sun or The Washington Post. It took postings on the Free Republic site, based in Fresno, Calif., to bring that gossip into the local papers of public record, as part of the story of a state official's resignation for helping to spread such chatter.

Free Republic, a conservative discussion site, was also among the Web sites that took the lead in casting aspersions on a now-discredited 60 Minutes report on President Bush's Vietnam-era National Guard service. Ultimately, CBS was forced to investigate its own story and fire key staff members for failing to adequately verify information before airing it.

The Web site's treatment of the O'Malley rumor and the 60 Minutes report underscores the dual nature of this new form of communication, which traffics in unsubstantiated rumors but can also serve as a check on the mainstream media.

Such sites combine the dish-the-dirt atmosphere of a neighborhood bar with the global reach of the Web, said Rich Gordon, chairman of the Newspapers and New Media Department of the Medill School of Journalism.

Whether or not the upshot is a better-informed public, the old-time media must learn to respond to alternative sources of "news," he said.

"Here we have this wonderful universal publishing medium that allows anybody to post information or opinion, and anybody in the world can see it," he said. "We have opened up the publishing system to people who have an agenda.

"The threshold, what it takes to get the story out in the public, is a lot lower," he said. "There are going to be situations where the mainstream press feels it has to cover something it wouldn't ordinarily."

Of course, online news sources can be, and often are, wrong. In 2004, Matt Drudge - the blogger best known for breaking the Monica Lewinsky scandal - posited online that Democratic presidential candidate John Kerry was having an affair. But when the mainstream media began chasing that story, it proved groundless.

As the Kerry rumor demonstrated, journalism experts said, bloggers and other Internet posters write by different standards than mainstream print reporters. Conventional rules of journalism dictate that information is verified before it is published; for better or worse, many Web sites don't follow the rules.

"There is an affirmative philosophy to the blogosphere that is very different from journalism - that philosophy is, in effect, publish first and verify later," said Tom Rosenstiel, director of the Project for Excellence in Journalism, an organization that works to raise journalistic standards.

The dangers of this are clear, he said, especially to public officials who have few ways to fight back when gossip about them is spread: Even denying a rumor legitimizes it and makes it fodder for the mainstream press. Some Web sites, then, degrade rather than further public dialogue, Rosenstiel said.

"It creates an opportunity for people who are not simply citizens but who are political dirty tricksters to use techniques that can only be considered Nixonian - to engage in smear, to engage in rumor campaigns - and there really isn't an upside to that for anybody," he said.

But Web-born news has its merits, said Jay Rosen, a journalism professor at New York University and the author of the blog Pressthink.org, and comparisons with traditional media aren't necessarily relevant.

"It's like comparing a public park to a living room," he said. The Web is "an ungated space, versus the opposite of it, The Baltimore Sun, The Washington Post, which are gated, literally. They're filters. That's where the heart and strength of the news establishment lies.

"The Internet has a different basis for strength, and that is openness."