Have been looking for a HTML5 game engine for a couple of days. Had almost decided on using Impact but realized that it didn't use a scene graph. I really needed that kind of feature so decided to keep looking.
Tileset and sprites by Oryx Design Lab
I have tested using IE9, Chrome, Fifrefox and Safari on iPhone 4. Kind of slow on iPhone but didn't expect anyhting else really.
What framerates do you get on your device? Please post below :)