On its official blog Thursday evening, under the title, Encouraging People to Contribute Knowledge, Google announced the first phase of testing of a tool designed to facilitate the organisation of "authoritative articles" written by users.

The tool, dubbed "knol" for unit of knowledge, will be similar to other online encyclopedias such as Wikipedia. According to Google, knols would "cover all topics, from scientific concepts, to medical information, from geographical and historical, to entertainment, from product information, to how-to-fix-it instructions."

In addition, site will be ad-revenue driven and authors who choose to allow advertisements on their knol will be able to share in "substantial" revenue derived from the ads. The pay scale was not revealed in the announcement.

The content of the articles will not be vetted by Google. "Google will not serve as an editor in any way, and will not bless any content," said Udi Manber, Google VP of Engineering in the announcement. "All editorial responsibilities and control will rest with the authors," continued Manber. "We hope that knols will include the opinions and points of view of the authors who will put their reputation on the line."

Similar to wikis, the content of the knol site will be editable by users. "People will be able to submit comments, questions, edits, additional content, and so on," said Manber. "Anyone will be able to rate a knol or write a review of it." It was not made clear whether users other than the author would have to be registered or if anonymous editing would be allowed.

Wikipedia founder Jimmy Wales had a wait-and-see approach to Google's latest offering, in an interview on Friday. "Google does a lot of cool stuff, but a lot of that cool stuff doesn't work out so great," said Wales. Commenting on the revenue-sharing aspect of the Google knol, Wales predicted there may end up being a focus on less academic submissions. "You may see an awful lot of articles about Viagra," said Wales.

One role Google will play is to rank the submissions, or knols, in Google search results and suggested the content would be made available to other search engines. "We are quite experienced with ranking web pages, and we feel confident that we will be up to the challenge," said Udi Manber. "We are very excited by the potential to substantially increase the dissemination of knowledge."

Google suggested that the tool is still in development and gave no indication of when it would come out of the testing phase and rolled out to the public. Testing is being carried out by an invitation-only group of participants.