You’ll want to make sure you are using nightlies, and not 0.2.4. I think nightlies works okay with xbmc. Or last time I tried it did, anyway.
One of the last 3 nightlies worked fine with it IIRC. I’ve not managed to softmod my own xbox yet to get XBMC set up.
It is a bit annoying that XBMC can’t connect to iTunes 7.x shares though, hopefully they’ll fix that in a upcoming SVN version.
Probably won’t… apple keeps changing the encryption scheme whenever someone figures it out, so nobody is much interested in continuing to chase it down.