Google is countering with its own HTML5 site called HTML5Rocks. HTML5Rocks features several tutorials on HTML5 feature. And there’s a code playground to let you mess around with your own code. Obviously, all of this works well in Chrome because according to Google presentation was originally meant to run in Google Chrome. Some experimental features might or might not be coded to run in other browsers for now. I tested the site with Firefox and pretty many things worked well and same examples failed to work as expected. HTML5Rocks seems to be a great new resource for developers looking to put HTML5 to use today, including more than just basic information on specific features and when to use them in your apps.
Google and Apple are arguably the two biggest companies attempting to push HTML5 forward. Notably, both also dominate updates to the WebKit rendering engine (with both Safari and Google Chrome use). Mozilla is also actively pushing HTML5 forward. And Microsoft also seems to be following on at the HTML5 development. All of them have their own HTML5 demo pages on-line.