By Tom Henderson and Rand Dvorak (Network World)
Hyperic HQ is an open source monitoring and management application that's designed to control VMware's ESX servers and the virtual machines hosted on them. The product can be used with VM-hosted applications and operating systems, or on individual operating system or application components; it’s one of the most mature open source projects we’ve tested.
Overall, we have to say that HHQ is a really strong "meta" console for VMware environments.

http://www.networkworld.com/reviews/2007/121707-virtual-management-hyperic.html