Very much a work in progress. This took about 15min over a wireless connection, for 3000 songs on my Powerbook to the desktop machine. Shouldn't be used on anything other than 10.4 Tiger because the "E" flag is specific to that version, which keeps Apple resource fork information when copying.
rsync -rtE --progress iTunes/iTunes\ Music/ yourothercomputer.com:/Volumes/MaxtorBlue/Music
You'll be prompted for your password on the remote machine (assumes you have the same username on both machines).
- r: recurse into directories
- t: maintain the time stamp on the files
- E: keeps Apple resource forks intact
- progress: scrolls by a list of transfers and how long they take