I ran into an interesting symptom of presenting snapshotted vmfs volumes from my production vSphere4 clusters to my isolated lab environment which is a ground up build of vSphere5.
In looking at the resource allocations for virtual machines imported into the inventory I found that the machines had memory limits applied that matched the configured vRam setting. Checking my production environment I confirmed no limits had been applied and creating new virtual machines in my lab were set to unlimited.
Not sure why this occurs, hopefully it doesn’t occur in an upgrade!