If there are any mainstream journalists who still doubt the value of 'citizen journalism' (and what others call grassroots journalism), the events in London on Thursday showed how wrong those doubts may be.

All day long, sites like the BBC and The Guardian carried photos shot by survivors of the three  subway blasts. The photos, taken with cellphone cameras, were often eerily effective at conveying the subterrenean hell the tube had become for many people. But they also showed the calm and sense of purpose exhibited by those same people in a danerous situation. The BBC later reported that its website had received almost 1000 photos taken by cellphone and 20 pieces of amateur video.

In a piece for the Washington Post entitled "Witness to History," Robert MacMillan writes that on Thursday citizen journalists passed the breaking news test. He points out that there have been cases in the past when mainstream media have used the efforts of people on the scene for their reports - Abraham Zapruder's film of the assassination of President Kennedy being perhaps the most famous example. But MacMillian believes that "citizen journalism is different."

It often covers a wide territory from soliciting arts and entertainment coverage to providing the angle on the city council budget that the cub reporter might have missed.

The London attacks moved the trend to a new level. Web sites from the BBC's to the Guardian's provided eyewitness accounts, some showing up as little as an hour or two after the first bomb went off. Rather than relying on unfocused, rambling blog entries, the London papers and the Beeb ran pithy postings from the people who were there. They ran alongside the staff reporters' accounts and presumably with the same amount of editing.

Dan Gillmor, formerly of the San Jose Mercury News and one of the leading proponents of 'participatory' journalism, makes the point in MacMillan's piece that what happened in London was different than what happened after the tsunami in Southeast Asia.

The tsunami prompted bloggers to post thousands of video entries and journal-style stories that circulated the Internet in a huge swarm of unedited data. London, he said, showed how that data could be edited like traditional news and fill the gaps that the news could not.

Gillmor has created a 'Citizen Journalists Pledge'. Dan asks people who sign up for the Bayosphere citizen journalism site he has created to cover the San Francisco area:

I report and produce news explaining the facts as fairly, thoroughly, accurately and openly as I can.

* Fair: I'm always listening to and taking account of other viewpoints;

* Thorough: I learn as much as I can in the time I have, and point to original sources when possible;

* Accurate: I get it right, checking my facts, correcting errors promptly and incorporating new information I learn from the community;

* Open: I explain my biases and conflicts, where appropriate.

Jon Dube's Cyberjournalist (a site associated with the Online News Association - note: where I'm the executive director) is attempting a comprehensive listing of all the current citizen media initiatives under way in cyberspace. Blogger Amy Gahran has also started "I, Reporter," a blog that looks at the issues around citizen journalists, and often offers suggestions on ways mainstream media sites can work with people in their communities interested in contributing.

This won't be the last time that we're hearing about citizen journalists. In fact, you can almost see them becoming a major component of all major news stories, especially ones like London. The media world is changing around us almost every day. And news organizations ignore ideas like citizen journalism at their own peril.