morb--this ability was removed over a year ago, with great reluctance. It was a *very* popular feature

It's called searching by hash, but turned out to be very "expensive" in terms of network stability (such searches were drowning out so much other traffic) that limewire had to ban such searches. Since then, only "keyword" searches are "allowed."

The gnutella developers have continued to discuss and try ways to get equivalent power in searches. I hope they can find a feasible way, but I'm not holding my breath.

If you want to know more about the history of such, let me know and I'll dig up the links