I mentioned PyBackPack recently and now here's another back-up tool, rdiff-backup. Rdiff-backup aims " to combine the best features of a mirror and an incremental backup." It lists the following features: easy to use, creates mirror, keeps increments, preserves all information, space and bandwidth efficient, transparent data format, filesystem feature auto-detection (wonder if it works with ZFS), Mac OS X Reference Fork support, ACL and EA support and keeps statistics.
To learn more, jump to UbuntuGeek's article detailing how to install and configure rdiff-backup.