We are currently evaluating Zimbra installed on CentOS5 and clients running Outlook2007 on XP and iCal on MacOS10.5.2.
If I create an appointment in either Outlook2007 or via the web interface the appointment time within iCal is incorrect. We currently have all timezones set to GMT+10 Brisbane/Australia and it appears iCal adds the +10 to the appointment (appointment for 10am-11am 15/03/2008 set in either webui or Outlook both can see it with the correct time however using iCal it shows as 8pm-9pm 15/03/2008).
I have set GMT+10 within Outlook Calendar/XP/ZimbraAdmin/iCal/MacOS and there doesn't appear to be a work around for this. I have also set the preferences of iCal with and without timezone support but this makes no difference.
Please let me know if you require further info to this problem.