From CBC.ca:

Google Inc. is testing a new user tool that invites people to write authoritative articles on particular subjects, a move that could put the internet search giant in direct competition with the popular online encyclopedia Wikipedia.

The user-generated knowledge project, dubbed Knol, was made available this week to a small group of users in a trial, said Google's vice-president engineering, Udi Manber, in a Thursday evening post on Google's official blog.

"We believe that many do not share that knowledge today simply because it is not easy enough to do that," wrote Manber. "Our goal is to encourage people who know a particular subject to write an authoritative article about it."

Google said it would provide tools for writing, editing and provide free hosting of the content. Authors would receive credit for their work and could choose to include Google ads on their pages, with authors getting a share of the revenue generated from those ads.

Multiple articles — called knols — on the same subject would be allowed. The articles would be ranked according to a reader voting mechanism.