Wow, the changes VMware made to vSphere 5.0 have really stirred up a lot of passion on the subject from angry customers. Is all of it justified? Probably not all, but certainly some customers will be required to purchase additional licenses for their existing environment when they upgrade to 5.0. But to help take some of the emotion out of the discussion, you first need to see what YOUR environment looks like. Since VMware hasn’t yet release their vRAM reporting tool a few VMware community members wrote some scripts to help people out. You will either be pleased by the results, or be stuck with a bill come upgrade time.
You can find a compilation of the scripts here. Users are posting results of their environment..so continue to watch the thread even after you download the scripts. There is also another license validator script that you can read about here.