How Microsoft IT Monitors and Manages the Exchange Messaging Infrastructure as a Service is a podcast available for download at the Microsoft site.
Overview: Managing Exchange Messaging Services by Using Metrics discusses how Microsoft IT improved its messaging services using targeted metrics and process. This white paper covers service level agreements (SLAs) and key measures that Messaging IT uses to determine service improvements and related decisions. The paper introduces service reviews and why they are an important component of running a service; includes sample scorecards of weekly and monthly reviews.
There's also a technical white paper about this subject: Managing Exchange Messaging Services by Using Metrics.