Avi Bryant blogged about his first concrete steps towards getting Ruby running on top of a Smalltalk VM. He calls it Smalltalk.rb
I’m pretty sure this is the lightestweight bootstrap there can be towards the goal of eventually getting Ruby running on a Smalltalk VM. No new parser needed: we use JRuby’s. No new compiler needed: we use Squeak’s.
He also started a Google Group on it to get interested parties involved. I wish him and those the best of luck as this is very promising stuff.