What ever happened to Google Knowls?

It was announced on December 13th last year with much discussion here on DLTJ and elsewhere on the blogosphere. It would seem uncharacteristic of Google to announce something like that and keep the world waiting for months to see at least a beta of the concept. Is there some sort of technical problem with the concept? Legal or business model problem? Or was it just a trial balloon for a service yet to be developed and Google wanted some free market research from the community?

Anybody know?