I’ve been using a Zimbra account for the past couple of weeks and have found it not to be reliable in syncing my desktop and laptop (both Macs). Yesterday, I was looking at iCal on both machines plus the web interface. I kept synching both machines, but all 3 screens remained different. I had to maually create copies of the appointments on the other Mac, then the web client got duplicates. So I’ve been considering giving up on Zimbra entirely.
I haven’t even gotten OTA sync for the BlackBerry hooked up yet, but if I can’t count on the sync – the only thing I want from it – I can’t use it. Google Calendar is looking better and better.