Knol has been discontinued as of May 1, 2012 ([knol.google.com ])

Below is the message Google posted

"

Knol has been discontinued as a service, but we've worked with Solvitor and Crowd Favorite to create Annotum, an open-source platform based upon WordPress that allows you to continue authoring and publishing scholarly articles. Viewing and editing knols is no longer available, but you will be able to download them to file through October 1st, 2012.

"

So if you have any Knol's, download them before 30th August...Looking forward to "Annotum" a new open source platform!