David Van Couvering wrote a great article on sync between a local client and a server:
Synchronizing a Web Client Database: LocalCalendar and Google Calendar. This is a great companion to the piece I wrote for O'Reilly a while ago,
Creating Desktop Apps with Java-Based Web Technologies.
Nice reminder of all of the stuff still on my list of
things to be done (check out #7, sync...).
I haven't touched the stuff on Canteen in a while - if you're interested,
drop me a line to remind me to update it...