It’s certainly a lot harder than your average Unix. I haven’t tried any of the GUI products, but I tried and failed and ran into most of the documented problems with the usual tools. I’ve got a long blog post unpublished on the whole process, that might see the light of day some time.

The thing I’ve found that works for me so far ( for some value of works that involves not skipping files, corrupting things, or blowing up and refusing to sync ) is Unison, ( http://www.cis.upenn.edu/~bcpierce/unison/ ) which, although not expressly designed to be such, can easily be convinced to work like rsync, and doesn’t go nuts over HFS+ quirks, like every other mac rsync I’ve tried ( including the Apple one, that’s supposed to do resource forks and whatnot, but is useless and explodey )

I just use it to sync /Users on various macs nightly to a network RAID, It probably wouldn’t be too hard to script something more sophisticated around it.