In general it should work. It's not been tested extensively so we can consider it fully *supported* yet. I don't think the GAL would sync or shared calendars but I've not tested this myself. I've got a PocketPC PDA myself and have been testing out over-the-air sync. It's still in internal beta but it'd super sweet. So I can totally recommend PocketPC as a good device to sync with Zimbra. You'll be able to see for yourself once this is available for public beta.