KaZaA - Support for this is a possibility, but I'm really not sure how long Shamen Networks will last with legal issues and all and whether KaZaA will continue to run in the future.
SpyWare - Doesn't Oregano 2 (or at least the demo) check for updates upon startup? I seem to remember it automatically updating itself a while ago.
Centralisation - It's true that Gnutella does use Super peers (called 'Ultrapeers', on Gnutella) but I still wouldn't call this centralisation, as the choice of which nodes can become Ultrapeers is totally dynamic. I don't think there is a total reliance on these, as all servents should be able to fall back to classic Gnutella mode, which CocoGnut uses. Also, if many/all Ultrapeers fail, more will arise because nodes will sense the need for more.
Gnutella's previous point of centralisation was host cachces, which provided a list of IP addreses to connect to. This isn't really the case anymore, as IP addresses are now located via GWebCaches - a system of WWW sites which provide IP addresses and URLS of other GWebCaches. As long as clients are provided with the URLs of some GWebCaches, as long as not all of them are down, there is no central point of connection.
Freenet - Is nice, admittedly! It's more anonymous than Gnutella, but from my experience of it (this was a while ago), slow, very difficult to connect to and hard to acquire files, eg. MP3s.