I've seen this floating around the codebase for a while, but only recently I believe the documentation (wiki) was updated with info on this parameter. In the production version of solr i'm using (actually a nightly build from few months back), this is still not supported though, so I believe this feature should be marked with the 'Solr 1.4' flag on the wiki so people know this is a future/nightly-release feature..
-Chak
