Ok, so Microsoft finally has release some information I have been dying to talk about with respect to Exchange 14. Microsoft is preparing to release with Exchange 14 a managed API for Exchange Web Services that can be utilized by developers to access Exchange data within mailboxes such as folders, email, calendar, contacts, etc… The Web Services approach is nothing new as it existed in Exchange Server 2007, but most applications written for Exchange Server 2003 or 2007 still used WebDav. Exchange Web Services is the new WebDav. There is already a sample Vista Gadget available today to demonstrate this functionality.
Go here to get more information on Exchange 14 Web Services and the announcement
Go here to read more about the Managed Web Services API from MSDN.