The following document exists...
Virtualization Guide for Cisco Unified ICM/Contact Center Enterprise & Hosted, Release 7.5(3), November 2008.
It describes running PGs and Client AWs within a VMware ESX environment. The idea being running a centrally hosted ESX box running PGs connected to remote ACDs (where supported).
My question. Are any other ICM versions officially supported on ESX other than 7.5(x)? The doc doesn't explicitly comment on previous versions.