VM Ware have their greatest and finest solution of virtualization of hosts/ clusters and network
I happened to build a feature to manage distributed virtual switch using APIs.
VMware Infrastructure (vSphere) API and it is excellent and easy to use.
Not to say easy to setup because that is how all the VMWare products have been made to be harder to use initially.
http://vijava.sf.net/
http://www.virtuallyghetto.com/2011/12/retrieving-information-from-distributed.html
http://www.virtuallyghetto.com/2011/12/retrieving-information-from-distributed.html
