Very quietly, VMware released some information about vSphere for Desktop. This is the licensing model you’re going to want… especially for VDI.
Here’s a link to the details:vSphere Desktop FAQ
There are a number of caveats explained in this FAQ, but the licensing strategy is beginning to make sense.
In short, if you run VMware View, you can get an unlimited vRAM entitlement. You cannot upgrade to vSphere 5 for Desktop and if you’re running a third-party VDI solution on vSphere, you will have to use the “non-Desktop” editions and be subjected to vRAM license limits.
This is just my humble opinion and does not necessarily reflect the opinion of my employer or partners or anyone else for that matter