Duplimats from the wiki looked cool but I haven’t heard about it lately and the site doesn’t suggest any further development. Any one know?
The coder of this project states:
“…the underlying problem is the same as always: a secure anim-repeatable way of identifying individual copies of objects including duplis and particles. As soon as the renderer can identify a serialnumber for each object, duplimats are pretty easy”
Currently some discussion is being done about a feature which would remove this limitation. You can find it here:
http://mediawiki.blender.org/index.php/BlenderDev/ObjectModifiers