MacGeeks - I have been semi-happily using SyncMate for the past few months, as I gave up hope that MissingSync (MarkSpace) would ever get their shizzy together with Leopard. Whelp, to my overwhelming surprise, I found this today - an updated beta version that fixes a lot of the issues and...wait for it...adds MOUNT ability back to MissingSync! Woohoo!
Been running it all afternoon with zero issues and I am pleased to recommend it.
http://www.markspace.com/testing/
Cheers!