From now Exchange 2010 is completely supported to be run in a virtualized environment.

This also includes the unsupported features:
– Unified Messaging server Role
– Combining Exchange 2010 DAG ( Database Availability Groups ) with hypervisor-based clustering, high availability and migration solutions that move automatically failover mailbox servers that are members of a DAG.

The vendors that participate in the SVVP can be found here:http://www.windowsservercatalog.com/svvp.aspx?svvppage=svvp.htm

The whitepaper “Best Practices for Virtualizing Exchange Server 2010 with Windows Server® 2008 R2 Hyper V™” is also available and can be downloaded from here:
http://www.microsoft.com/download/en/details.aspx?id=2428

The hardware requirements for virtualization can be found here:
http://technet.microsoft.com/en-us/library/aa996719.aspx