On the same date vSphere 4.1 was released, VMware announced it will change it’s licensing policy for several of it’s management software ( vCenter Capacity IQ, vCenter AppSpeed, vCenter Site Recovery Manager and the Ionix management line).
Licensing used to be based on the number of CPU-sockets in the host running VMware. This made Site Recovery Manager for example a relative expensive solution. Many customers like to protect some of their virtual machines using SRM, but not all. In the old model they had to either buy licensing for all of their hosts, or create a separate cluster running VM’s needed to be protected by SRM.
The new license model is based on the number of vitual machines which are managed or protected by the VMware software.
Read more here http://itknowledgeexchange.techtarget.com/server-virtualization/vmware-adopts-per-vm-licensing-pricing/
and at virtualization.info http://virtualization.info/en/news/2010/07/vmware-to-adopt-a-per-vm-pricing-model-starting-september-1st.html