A recurring question we get on Ask TUAW concerns managing multiple iTunes libraries, particularly keeping them in sync, whether for one user with two computers (e.g. laptop and desktop) or between multiple users with multiple machines (e.g. family members). It was with some interest, then, that I recently ran across Syncopation from Sonzea which promises to automate the process.
It will allow you either to clone a full library on two machines, or selectively sync your files (video as well as audio) via iTunes playlists or within the application itself. This could be very handy, for instance, if you want to keep an automatically updated subset of your music on your Mac portable with limited hard drive space.
Syncopation is $24.95 (for use on two Macs) and a demo is available. If you've had good experiences with Syncopation or other iTunes syncing tools, please let us know below.