Today, Exchange Server 2010 Release Candidate is feature complete and available for download here. There is a great little interview located here (and the full announcement):

http://msexchangeteam.com/ 

There are some cool new things in the Release Candidate:

  • Support for Windows Server 2008 and Windows Server 2008 R2: The Exchange Server 2010 Release Candidate is now supported on the 64-bit versions of the Windows Server 2008 and Windows Server 2008 R2.
  • In place upgrade from Exchange Server 2010 Release Candidate to Exchange Server 2010 RTM: You can start planning and deploying your Exchange Server 2010 environment today knowing that it will be possible to perform an in place upgrade with the final version expected to be available later this year. You won’t need to reinstall your servers or reconfigure your Exchange settings once you have deployed the Release Candidate. This will save you time while allowing you to start evaluating the latest product capabilities now.
  • Co-existence with Exchange Server 2007 and Exchange Server 2003: If your current environment is Exchange Server 2007 or Exchange Server 2003, Exchange Server 2010 Release Candidate is able co-exist with either of the two versions. This will enable you/your company to start planning your upgrade, test critical scenarios and experience the benefits of the latest version of the product. For Exchange Server 2007 co-existence, Service Pack 2 (SP2) is required, and will be available later this month.

For additional technical details, please visit Microsoft TechNet site under the “What’s new in Exchange 2010” section.