Excellent! Tim Roberts has started hacking away at an open-source, cross-platform accessibility validator he’s dubbed WaiZilla.
All testing is performed client-side, so results display in mere milliseconds instead of being delayed by a page refresh. Tim has set up waizilla.com for future downloads/documentation/etc.
He’s looking for volunteers, anything you can contribute would be appreciated. More detail over at AccessifyForums. A worthwhile cause, good show Tim!