You must...

That might be practically true at the moment, but as far as it has been "sold", Wave is supposed to be an open (whatever that means these days), distributed platform: http://sites.google.com/a/waveprotocol.org/wave-protocol/wave-community-principles

For all the (deserved) talk of sadness about Usenet's passing, isn't Google Wave a viable alternative? No "complicated" client to install, and it gets around the linking and distribution (i.e. caching) issues. I guess it's the categorisation that is lacking, although I can see that being solved with the help of good indexers (Google again?) and a sprinkle of microformats or somesuch.