[bsimpson]

I was expecting this to use WebGL shaders.

When image filters came to Flash, they used a technology called PixelBender, which computed the value of each pixel independently and parallelized them on the GPU to maximize performance. There's a similar proposal for CSS that uses WebGL shaders for the parallelizing:

http://www.adobe.com/devnet/html5/articles/css-shaders.html

Opera also has a writeup on doing this in WebGL now without CSS:

http://dev.opera.com/articles/view/webgl-post-processing/