In June, Google launched a new HTML5 resource site called HTML5 Rocks. They've now added a bunch of new content to it.

On this page there are numerous resources for reference and tools. This page has tutorials.

In addition to all of this, there is a new component of the site called HTML5 Studio. This is a place where you can view a number of demos that show off interesting uses of HTML5, CSS3 and related technologies.

On the Chromium Blog, Paul Irish with Google's Chrome Developer Relations department says, "If you want to not only get up to speed, but understand the browser differences and techniques for a robust implementation, please take a look through the new guides for implementing HTML5 video, understanding 'offline,' auditing your webapp with the Chrome developer tools, and using web workers and @font-face."
 

There is also an RSS feed now.

Google showed off another use of HTML5 via a Gmail game on Friday.