Martian Technology has released SlingShot 2.0, a major update to its network file synchronization application for Mac OS X. Version 2.0 adds the ability to synchronize iTunes music (songs and playlists) between two or more computers connected over a network — an easy way to back up all of your important (and costly) music. With SlingShot 2.0, you can Publish an iTunes Playlist of music onto the network and then Subscribe to the Playlist from other computers. SlingShot will copy over any songs from the Published Playlist that aren’t in the Subscriber’s iTunes Library, add them to the Library, and then recreate the Playlist on the Subscriber. Then it will check periodically to see if the Playlist has been changed; any changes will be reflected in the Subscriber’s copy of the Playlist. SlingShot is requires Mac OS X 10.4 or later, and is priced at US$29.99.