read at ars technica
"What happened to Knol? Announced by Google in late 2007 and launched in July 2008, the site was meant to bring more credible (read: not written by anonymous Wikipedians) 'knowledge units' to the web, and it would allow the authors to cash in on their work. But it's 2009, and Knol appears to be notable largely for its non-notability.
First, the good news. Knol users have already published more than 100,000 pieces of knowledge and the project has a (shockingly) quick schedule of incremental releases. According to the Knolologists of Google, 'people visit Knol from 197 countries and territories on an average day, from the Aland Islands and Antarctica to Zambia and Zimbabwe.'"