HTML5 rocks, but is this it?

Playing with HTML5 I stumbled upon http://www.html5rocks.com/ the google-sponsored site of HTML5.

A lot of cool feature and examples, but in the code I found some webkit-only code.
Then I noted the footer of the page contains a disclaimer:

This site contains information on APIs that are not part of the current W3C HTML5 specification.

Is Google pushing its own specs?

Peace,
R.