there is a program called myTunes that allows you to access all itunes libraries on a network and download hard copies of whatever you want to your HD. I think apple made them pull it from versiontracker, not sure. it works great, does everything it should. cheers.
There's also syncOtunes, if both the Macs (or accounts on the Macs) are yours. I've tried using it, but it can take a while with a slow network. I do NOT recommend using it across the internet, IP over Firewire would probably be best (or target disk mode)