Mark A Sheldon has a Phd Thesis proposal (I have a copy) on Semantic Library systems, working in Dave Gifford's group. Semantic file systems have content lables (like README files) on directories which enable one to direct searching.
Dick Marcus (Tel 253-3240, Room 35-414, markus@lids.mit.edu) at the LIDS (Lab for Information ..????) at MIT ("just over the road") is looking at searching webs of infomation.