I've got a basic demo running:
- poly/poly collisions
- contact point & arbiters
- rigid body dynamics
- basic engine
I've fully OO'ed it - once its working I'll optimize it for Actionscript (a fun job, that will i part require manual inlining of all vector operations

A very very (very) basic demo of this is here: http://home.planet.nl/~borst595/pEngine.html
Next task - get that spacial hashing working.....