Exchange Server 2010 (download)includes a new “unified platform” for both high availability and site resilience that is very different from the high availability model and solutions provided in previous versions. Exchange 2010 includes significant changes at its core that integrate high availability deep in its architecture, making it even less costly and easier to deploy and maintain than previous versions of Exchange.  This and upcoming videos, will feature a tour of the new high availability features, such as database availability groups and mailbox database copies.

More info: Video