Recently, Microsoft added vSphere 5.0 as a supported hypervisor for Exchange 2010 to their Server Virtualization Validation Program support policy wizard. Exchange 2010 RTM and SP1 are both listed as supported running on Windows 2008 RTM and Windows 2008 R2 on vSphere 5.0. In addition, Exchange 2007 SP1, SP2 and SP3 are listed as supported on vSphere 5.0 as well but RTM is not.
Great news!