A big, high-profile, citizen journalism experiment from Yahoo! and Reuters called You Witness News will start accepting content Tuesday.  Yahoo! will accept submitted photos and video, and they will appear on Flickr with possible distribution to Reuters. “Editors will then screen it to see which content is worth promoting to news stories or be distributed to Reuters clients. Yahoo will use the content for its sports and entertainment sections, and the company said it will soon expand to local news and high school sports,” Lost Remote reported today.

This is probably the biggest citizen journalism effort in the short history of Web 2.0. The BBC, CNN and tons of newspapers and independent Web sites are also experimenting with citizen and collaborative journalism, but traffic to Yahoo! News, where You Witness News is housed, is very high, according to comScore.

Reuters President Chris Ahearn said in a New York Times article, “This is looking out and saying, ‘What if everybody in the world were my stringers?’”

Reuters is exploring the possibility of providing a wire service with entirely user-submitted photos and videos for client media organizations, The New York Times reported today. Reuters may split the revenue with Yahoo! and the person who took the video or photo. Nothing is set in stone, and the new service may depend on both Yahoo! receiving enough quality content and client media outlets expressing interest in the material.

But media outlets in smaller markets may be reluctant to use Reuters’ proposed new service if people in those towns aren’t uploading their photos and videos to You Witness News. We’ll be watching, but will users?