GitHub Using HTML5 History API.

Fantastic use of the HTML5 History API on GitHub’s project trees:

The new HTML5 History API (which really has nothing to do with HTML — it’s a JavaScript API) allows us to manage the URL changes while CSS3 transitionshandle the sliding. Permalinks are always maintained, your back button works as expected, and it’s much faster than waiting for a full page load.

The Tree Slider