I've been around stackoverflow pages, i found a mature framework http://logicking.com/index.php?page=html5 they called it ultimate.js, i tried to play this game on my iPod touch 4, the performance and device behavior is... wow.
Their site says they use directCanvas and CocoonJS. Those are the same two technologies we're working on for Construct 2. Hopefully they will be ready soon!
Develop games in your browser. Powerful, performant & highly capable.
Cool i can't wait!