It's made by googlers, but I don't think it's officially endorsed by Google.

"It's made by googlers"

Yes it is. One of the authors seems to be an "internal software development coach" (source: http://www.geekinasuit.com/2009/03/hiatus-should-be-over.htm...) at Google. The other author's blog seems to be down atm (http://jakeherringbone.com/).