iPhone and Zimbra
Zimbra (our hosted email solution) supports synchronization with the iPhone via POP3, IMAP and iSync. With iSync you can sync contacts, calendars and address books.
Of course, the Zimbra Web Client is 100% compatible with the iPhone. Need more help? Zimbra put up a wiki page with instructions on how to set up your iPhone to talk with the Zimbra server. The Zimbra folks are also going to be at iPhoneDevCamp between July 6th and the 8th.
