I've done a lot of revision to my original paper on PMD to make it more easily digestable and understandable. The revision is at: http://tunes.org/~eihrul/pmd.pdf

I also have a language in the works (and in fact already have a implementation of it) based on PMD that is very much like Self, only with multiple dispatch. :) I hope to release more information as the system solidifies in the coming weeks and becomes more polished.

Lee