Server Virtualization Validation Program (SVVP)
Have you heard of the Server Virtualization Validation Program (SVVP)?
It's a program whereby certain 3rd party virtualisation partners can validate certain configurations with Microsoft. This means the customer can get Microsoft based technical support for systems running in 3rd party virtual environment. Current list is as follows:
Cisco Systems, Inc.
Citrix Systems, Inc.
Oracle, USA Inc.
Virtual Iron Software
You can find some info from VMWare here: