I remember asking someone once why a certain IRC-client couldn't have an interface like an IM client instead of the regular notify list. Although most people on the channel I was in simply didn't understand, the people that did understand simply seemed not to want it.
IRC could probably be used for a million things, and I'm sure you could easily find an open-source IRC client and rebuild it yourself. However, authors of IRC clients in general are not gonna want to add bizarre features like swarming downloads to a client which was actually not built for P2P at all.
So the moral of the story here is you're gonna have to do it yourself, and please please make it open-source, because program monopolies are never any fun. Perhaps instead of Gnutella, you coul try building a BitTorrent client/tracker into an IRC client and see if that works? If you're not worried about anonymity, that is.
