Microsoft Exchange Server 2010 SP1 Beta Web Services SDK June 2010 Released
This release of the Exchange 2010 Service Pack 1 (SP1) Beta Web Services Software Development Kit (SDK) provides new and updated documentation and samples for building applications that use Web services in Exchange 2010 SP1 Beta. Use this SDK to help you develop collaborative Web services–based enterprise applications.”
Get it here.
MCM: Exchange 2007 | MVP: Exchange Architecture