PCI DSS 2.0 addresses use of server virtualization | Virtualization – InfoWorld

Implement only one primary function per server to prevent functions that require different security levels from co-existing on the same server. (For example, web servers, database servers, and DNS should be implemented on separate servers.)

Note: Where virtualization technologies are in use, implement only one primary function per virtual system component.

via PCI DSS 2.0 addresses use of server virtualization | Virtualization – InfoWorld.