Re:before anyone else does it... (Score 3, Interesting)

I don't know anything about whether iSync will require .mac in 10.4, sorry. But I did want to bring a piece of sync software to your attention: Unison. http://www.cis.upenn.edu/~bcpierce/unison/

It works wonderfully well. It's a little cleverer than rsync in that it will do bi-directional updates (ie syncing) and also merges conflicts if it is able.

I work on two macs and with unison I am pretty much able to work on either one without having to worry about which one is up to date.

I have .mac too and that does a nice job of syncing iCal and Address Book and my Safari bookmarks. But I think Unison would probably do a pretty decent job of that too, although I have not tested that out.