I've noticed that contact photos don't work with ActiveSync in iPhone 2.0. I can attach photos to contacts and Zimbra will be updated, but I won't be able to see previously set photos sync'ed/added by the phone (if I restore my phone per say and reconfigure ActiveSync settings).
Also, has anyone noticed the effect ActiveSync has on battery life with Zimbra? I've noticed one of our phones go down in 2 hours when sync'ed with ActiveSync and only received 1 email in that time period. What about regular ActiveSync services and Exchange? Has anyone measured the difference in battery life?