Dave and I at least are old chums of Ken Kahn, who was at PARC while we were designing Self there.
Ken's current work is a natural outgrowth of his interest in (of all things) prolog-like languages, and his interest in animation.
Other neat things Ken has done include Visual Janus, and, much earlier a system called Dierector at MIT.
If anyone wants his e-mail address, let me know. Ken is currently trying to productize this system, which is really cool for an interesting meaning of the word "cool."