What edits on Wikipedia have been made by people in congressional offices, the CIA and the Church of Scientology? A new online tool called WikiScanner reveals answers to such questions.

As the Web encyclopedia that anyone can edit, Wikipedia encourages participants to adopt online user names, but it also lets contributors be identified simply by their computers' numeric Internet addresses.

Often that does not provide much of a cloak, such as when PCs in congressional offices were discovered to have been involved in Wikipedia entries trashing political rivals.

Those episodes inspired Virgil Griffith, a computer scientist about to enter grad school at CalTech, to automate the process with WikiScanner. (It's at http://wikiscanner.virgil.gr but intense attention has knocked it out of service many times this week.)

The free Scanner grabs the Internet Protocol addresses used in anonymous Wikipedia edits in the past five years. By combining that with public information about which IP addresses belong to whom, the Scanner reveals Wikipedia changes made from computers assigned to a bevy of organizations, including, um, The Associated Press.

Many of the edits are predictably self-interested: PCs in Scientology officialdom were used to remove criticism in the church's Wikipedia entry. But others hint at procrastinating office workers, such as the tweaks to Wikipedia articles on TV shows being made from CIA computers.

Many examples are being tallied at http://wired.reddit.com/wikidgame - a page run by Wired News, which reported earlier on WikiScanner.

Griffith wrote on his site that he hopes ''to create minor public relations disasters for companies and organizations I dislike.''

Whatever comes of it, WikiScanner has a fan in Wikipedia founder Jimmy Wales. ''It is fabulous and I strongly support it,'' Wales told the AP.