Exchange 2010 Beta SDKs, Exchange Web Services Managed API 1.0 SDK Released

Microsoft released Exchange 2010 Beta SDKs. For Exchange 2010, documentation for each technology area is published in a separate SDK, making it quicker and easier for you to find information that you need.

Download:
Exchange 2010 Beta Web Services SDK June 2009
Exchange 2010 Beta Transport Agents SDK June 2009
Exchange 2010 Beta Backup and Restore SDK June 2009

The Exchange Web Services Managed API 1.0 SDK is also available, and contains information that can help you use EWS to develop applications for Exchange 2007 SP1 or Exchange 2010.

More Info: Introducing Exchange 2010 Beta SDKs | Guide to Exchange 2010 Development Technologies