Hallo!
My bro Josh Steiner and I wrote serendiPd (http://at.or.at/serendiPd ) a while back to do collaborative Pd performance, but also to do shared patch editing as well. Its stuck at the alpha stage because its not really possible to do shared editing well without a ton of work. Shared patch playing is feasible currently and could probably be made work decently with some work.
This will be possible with DesireData, but I don't know how far the current development is and when it will be useable ...
LG Georg