Because this is all done via HTTP, it is possible to reverse engineer the protocol -- in fact, Zimbra has already done this, and WM5 devices can sync with a Zimbra server the same way they would an Exchange 2003 sp2 server. Reverse engineering OWA WebDAV (an extension of HTTP that allows users to manage files on a Outlook Web Access server) service is also nothing new, as Ximian first did it almost 5 years ago with its app Evolution, bringing Exchange Server functionality to Linux. It is also not new for Apple, which has used it to sync OS X users' Apple Mail and Address Book with Exchange since OS X 10.3. Coincidentally, this is also how Microsoft's own Entourage connects to Exchange, versus using MAPI (Microsoft's Proprietary mail API) like Outlook. As important as up to the second email is to business users, we don't see how Apple could afford to leave this feature out.