I just got an email from Bryan Semple at VKernal, a regular correspondent with an insightful perspective on virtualization. He says, "Today, VMware announced that they would discontinue vRAM-based licensing for vSphere. This will make vSphere licensing once again based off of CPUs in physical hardware.
"As you can imagine, this is a dramatic change from this time last year. This update in pricing removes any apparent cost “penalties” for achieving a high VM density. In other words, the higher the VM density, the less hardware a data center will need to purchase, now with no additional 'vTAX'."
Bryan and his colleagues at VKernal have created an extensive collection of white papers and free tools. It can be found at: http://www.vkernel.com/vm-density-management-resources