Whoa, interesting ... I'm particularly curious as to what performance improvements he will go over.

I've been working on a little html5 game engine myself. It lets you use sprites in a retained mode like API, while still giving you an immediate mode interface to manage the game logic. It's still pretty early, need to do more work on some samples and documentation, but there are some docs there in the wiki :)

https://github.com/joelmartinez/flatredball-js