LimeWire is not actively making use of file hashes yet. That's one of the things I changed in my modified version.

I modified the IncompleteFileManager to create the temporary filename from the sha1-hashes (if available) so files with the same hash will always be swarmed from. I also modified TableLine.java to group search results in the search window only if they have the same hash.

http://mitglied.tripod.de/mdsgeist/LimeWire.zip