automatic requeries were banned about a year or more ago, because they were discovered to be HORRIBLY expensive. The developers were very reluctant to give up this obviously desirable feature that is so easy to code, but the network's survival was being threatened.

Basically, IIRC, auto-requeries by hash were found to be crowding out tranfers.

Attempts were made to limit them to 1 per client per hour, but even those had to be banned.

Occaisonally someone on the Gnutella Developers Forum http://groups.yahoo.com/group/the_gdf/ will try to suggest another technical change to the network to allow automatic researching, but so far no feasible solution has been found.

Currently the network topology and modern clients have managed to get more generally effective downloads in other ways.