Microsoft introduced a feature in Windows Server 2012 which enables snapshots to be reverted on Active Directory Domain Controllers without corrupting the Active Directory. This feature called VM-Generation ID also allows cloning of Active Directory running on virtual machines.
VMware vSphere 5.1 does support this feature since its release but I have not read a lot of information on it. Only recently VMware wrote a blogposting titled Windows Server 2012 VM-Generation ID Support in vSphere about the support.
--> Please see the rest on the blog, and start the Magic! : http://up2v.nl/2013/01/27/vmware-vsphere-5-x-supports-windows-server-2012-cloning-and-snapshot/