ITS has recommendations for Mac users on the the use of Apple Mail and iCal as your desktop clients for Zimbra:
http://www.stanford.edu/services/emailcalendar/desktop/applemail/index.html
iCal does a great job of keeping a cached local copy of your calendar which will sync the next time you have a network connection. Once
events are in iCal you can set all sorts of reminders including emails, pop-up messages, even the running of a script. Unfortunately, I've only been able to get events to copy over their alert type from Zimbra (alert messages x minutes beforehand) and then change them manually to an email alert once in iCal. Perhaps there's a way to have that happen automagically?
This connection was set up between Zimbra and my laptop's iCal app though I did not install the Zimbra connector for iSync* which ITS distributes here:
http://www.stanford.edu/services/emailcalendar/desktop/applemail/d_isync...
INSTEAD, I created a standard CalDAV connection using the basic instructions here**:
http://www.zimbrablog.com/blog/archives/2008/03/caldav-leopard-goodness....
In step #7, I entered "https://zm06.pobox.stanford.edu" as URL for the Zimbra Web Client.
This process can be replicated with shared Google calendars (see: http://code.google.com/p/calaboration/) as well, leading me to realize the power of iCal as one's desktop calendar aggregator-- wherever those calendars might exist. With data scraping built-in to Apple Mail, it makes for a compelling pair.
Do note that iPhone 3.0 now supports CalDav so this functionality can be replicated on those devices. Good instructions for connecting to Google can be found here:
http://www.bagofspanners.com/2009/06/17/subscribing-to-google-calendars-...
* It seems the Zimbra connector for iSync will allow you to sync your Apple AddressBook and Zimbra address books as well as allowing you to reply to event invitations directly in iCal. Haven't sussed this all out, but it seems that most of the previous functionality as well as some new bells and whistles are available. If anyone can speak more authoritatively on why the Zimbra connector for iSync is the way to go, please add it in the comments.
** alternate instructions with a little more detail here:
http://wiki.zimbra.com/index.php?title=CalDAV_with_Leopard_iCal
