In a recent article I posted a list of hypervisors that are supported by System Center 2012 (See https://garvis.ca/2013/01/28/system-center-vmm-supported-hosts/). I have since been informed that although this list of hosts may work, the only supported hosts are indeed as listed in the TechNet article. ESXi 5.0 is not supported, nor is ESX or ESXi 4.0.
I apologize for this error. I have used and managed these environments from System Center and I assumed that they were supported.
Thanks to Robert Larson for the clarification!