Well, I am writing a new client because my thesis advisor wants me to measure the performance of Gnutella. Thus, I need to measure the time taken to search, download etc.
So if you know of any modification of Gnutella doing this already, I would be glad to help with the advancement of Gnutella.

Also, I just bumped across this Java API for Gnutella called Jtella. (Just thought it was worth mentioning!)

Munjal