The Center for Internet Security is starting the process of drafting a benchmark for vSphere 5. New contributors are very welcome and can sign up at the link below.
Many of the elements in the vSphere 4 benchmark carry over to the vSphere 5 benchmark. Many elements do not, most notable is the absence of the console operating system. Also, while some of the elements are similar (i.e. presence of a firewall) the techniques to remediate or audit those items will be very different.