This cocept looked really promising but probably isn’t compatible with current nodes in 2.42, I wonder if there is any chance it will continue though. I love the idea of affecting particle materials in a non unfirom way.
http://mediawiki.blender.org/index.php/BlenderDev/DupliMats
The guy developing it was Ed Halley I think. I would be cool if this eventually became a feature in blender…
IIRC, Ed said that the implementation of this feature would have to be re-thought out following the changes in the upcoming 2.42. It was either the nodes or the dupligroups that caused some clashes.
Also, congrats to Ed for gaining cvs write access. 
Aligorith