Google has just announced a new initiative called Knol, which will compete with Wikipedia.
Unlike the anonymously written articles on Wikipedia, the articles in Knol will be signed by their credentialed authors and will rise in Google's PageRank like other web pages. Reader's will be able to rate the articles and provide comments to the author.
Google will provide both the web hosting and the authoring interface tools for Knol. Authors may optionally choose to have ads inserted into their articles, in which case they will earn a share of the ad revenues.