vRAM discontinued for v. 5.0 as well
[disclaimer - I work at VMware]
"If you have vSphere 5.0, then this is the correct path for you. The biggest upgrade 5.1 offered over 5.0 was banishment of the accursed vTax. If you already bought in to 5.0, you've already paid it, if it were to affect you. "
Do note that you don't need to upgrade to use the new licensing model. As of august 2012, vRAM was discontinued, even for users still on 5.0.