The 2007 evaluation bits and documentation are beginning to get pushed to the Microsoft website for Office Communications Server.
I would like to point out the Microsoft Quality of Experience paper under Planning. Here is the overview from the download page -
This document introduces Microsoft UC Quality of Experience, an innovative approach that aims to provide all users with the best possible quality anytime anywhere. It combines a comprehensive, user-focused quality program incorporating all significant influencing parameters; the use of intelligent, adaptive end-points that have the real-time capability to monitor, pilot, optimize, and deliver the Microsoft UC Quality of Experience; real-time metrics of user’s perceived quality of the actual call experience for all calls, collected in Metrics CDR and processed by a UC Monitoring Server; and a new media stack optimized for unmanaged IP networks, capable of real-time adaptive and corrective actions to continuously optimize the user’s subjective experience