From Google's official blog announcing the public launch of Knol:
The web contains vast amounts of information, but not everything worth knowing is on the web. An enormous amount of information resides in people's heads: millions of people know useful things and billions more could benefit from that knowledge. Knol will encourage these people to contribute their knowledge online and make it accessible to everyone.
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.
Everyone knows something. See what people are writing about, then tell the world what you know: knol.google.com
I do think this type of service would be cool in our huge university. Right now, you need to author a traditional web page, hosted within a traditional organizational structure. So, as an IT employee, I don't have a place to post my specialized knowledge about 14th century eating utensils. Our current institutional repository was somewhat designed for this purpose, but it's so 1999ish.