Just posting this as a heads-up for other Mac users and admins.
After upgrading to Mac OS X 10.7.0 Lion I found a few issues with iCal and ZCS 7.1.1, but several of them seemed to have been fixed in the course of upgrading to ZCS 7.1.3 and Mac OS 10.7.2.
However in the past few weeks a couple of new bugs seem to have cropped up, the first having to do with autocomplete in iCal, the second with using "apple-style" delegation in iCal. The bugs are:
Bug 66406 - [iCal 5.0.1] autocomplete not working in iCal 5
Bug 67567 - [iCal 5.0.1] Delegated calendar not shown in iCal5
As suggested by the titles, there's a suspicion that these bugs are specifically due to the iCal 5.0.1 version included in Lion 10.7.2. Zimbra has opened bug reports with Apple (based on the comments in the bugs).
In the meantime, it might be a good idea to review the bugs to see workarounds, and to test Lion 10.7.1 vs Lion 10.7.2.