Patrick Pendergast (SCVMM Program Manager) has posted that there is a document out to help create PRO enabled MPs.
This is a 32 page document starting with explaining what PRO is.
Physical Resource Optimization (PRO) is extended through a System Center Operations Manager 2007 management pack.
PRO enables you to augment the available knowledge in the management packs to make recommendations or take actions that take advantage of the additional capabilities available when workloads are running in a virtualized environment.
PRO relies on Operations Manager 2007 to monitor and collect performance data from hosts and virtual machines within an environment.
Nice diagram showing how it all fits together.
This document goes into a lot of XML and so is not for the faint hearted!