This seems like it might be exposing a limitation of iCal in Leopard, or maybe the way the iSync Services Connector translates information between iCal and ZCS.

A user, using the Zimbra Connector for Outlook, creates a private event in her calendar and marks it so. When I look at it in the Zimbra web portal, it's private. I can't see it. Because, you know, it's private. But then, when I sync to Leopard's iCal via the iSync Services Connector, it's no longer private. Instead of just being a nondescript block of busy time, it comes into the calendar as the actual event.

It's probably an iCal problem (in that there's no way to mark anything private - I guess you're just required to have multiple calendars that you need to check/view at all times). Nevertheless, this is a significant issue...