Google announced that Knol is now open to everyone. They announced Knol back in December. Knols are authoritative articles about specific topics, written by people who know about those subjects. From their blog post:
The key principle behind Knol is authorship. Every knol will have an author (or group of authors) who put their name behind their content. It’s their knol, their voice, their opinion. We expect that there will be multiple knols on the same subject, and we think that is good. With Knol, we are introducing a new method for authors to work together that we call “moderated collaboration.”
With this feature, any reader can make suggested edits to a knol which the author may then choose to accept, reject, or modify before these contributions become visible to the public. This allows authors to accept suggestions from everyone in the world while remaining in control of their content. After all, their name is associated with it! Knols include strong community tools which allow for many modes of interaction between readers and authors. People can submit comments, rate, or write a review of a knol.
At the discretion of the author, a knol may include ads from our AdSense program. If an author chooses to include ads, Google will provide the author with a revenue share from the proceeds of those ad placements. We are happy to announce an agreement with the New Yorker magazine which allows any author to add one cartoon per knol from the New Yorker’s extensive cartoon repository. Cartoons are an effective (and fun) way to make your point, even on the most serious topics. http://knol.google.com