Apple has a page of demonstrations that emphasize the full possibilities of HTML5. As others have noted, it’s not strictly HTML5, as a number of these features are a function of WebKit. To make matters a bit more complicated, Apple’s version of WebKit is a bit more robust, in terms of cutting edge functionality, than Google’s — and I assume other browsers built on WebKit. That said, kudos to Apple for building there browser on top of an open source project and for making all their developments open source as well. That some of these cool new possibilities only work in Safari should goad other browser providers, especially — and obviously — those also using WebKit, to step up. This is the way to make the functionality of the web move forward.