Siggraph 2001 has a/some nice paper(s) on this.  I'd know more
but the slow boat finally delivered it here a few days ago and then 
I needed to hassle with customs (what do you MEAN it's free.  Them
there is nice books).

I was watching one of the videos and kept waiting for MPAA X
rating to come up though...

Dan Ingalls <Dan at SqueakLand.org> wrote:
> Jeff Szuhay <jeff at szuhay.org>  inquired...
> >Has anyone built any bone-based animation for
> >Squeak?
> >
> >(or is this an opportunity? He says with already
> >too much on his plate.)
> 
> It's an opportunity, Jeff.
> 
> I've wanted to do this ever since we got Squeak running.  I bet Andreas can tell you a thing or two about putting cylinders around the bones, and painting textures on them, too, once you get it going.
> 
> 	- D