That may be the one goal, but I think probably a bigger goal is to have animations that are handled by the browser itself (and not Flash), and can be written in lightweight code.

I thought that was the point of WebGL?

Honestly, this is the first I've heard of CSS3 animations as intending to be ultra-fast, but I admittedly haven't kept up on the HTML5/CSS3 discussions.

Can you cite a reference for me please?