Hey look - someone implemented Rendevous/Zeroconf on Windows: Howl (via Marc's Voice)

Update: also found a Java Rendezvous (via Don Park)

Update 2: Rendezvous/Music-related links (DAAP = Digital Audio Access Protocol):
- DAAP daemon and links to Java client
- One 2 Oh My God: a Java iTunes client that doesn't work with the latest iTunes 4.0.1 update
- Notes on the DAAP Protocol for those wishing to implement their own clients