Martian SlingShot - OS X file synchronization

TUAW reviews an OS X Tiger (10.4 required) sync application:

Martian SlingShot - The Unofficial Apple Weblog (TUAW) $30

This little gem of an application allows you to keep two folders on different Macs (on the same local network) in sync, using a schedule.

Why would you want to do this? Well, perhaps you have a folder full of documents that two people in your house need to use, set up one Mac as the 'publisher' of that folder using SlingShot and the second Mac as a subscriber and you're all done.

I'd like to sync my iBook to one of my iMac folders, but the iBook runs 10.3.9. I suspect this app uses the SyncServices built into OS X Tiger. (Apple uses them for .Mac synchronization.)