Since CSS 3D transforms require the GPU you will need either Chrome or Safari running on a computer which supports GPU acceleration. Chrome on Windows XP, for example, does not allow use of the GPU by default so you wouldn't see WebGL or CSS 3D transforms
I'm in Firefox 4 on Windows, which does support WebGL, and all I see is blankness.
It's using CSS 3D transforms not WebGL :)
Sounds like you're on Windows, but FWIW it works in Safari on OS X.