My prototyping framework http://framerjs.com uses the exact same approach, divs positioned with only css matrix transforms. Great for high performance animations.

I've sometimes thought about building a full fledged ui framework on top of it but it doesn't work (exactly the same) in all browsers. And I suspect offloading everything to the gpu by default will lead to other sorts of performance issues but I'll have to test this.

Framer also includes spring physics and is fully integrated with Photoshop. You should check it out if you build prototypes.