For the Exchange 2007 architects out there, Microsoft have released a comprehensive (over 500 pages) document detailing the architectural changes from previous versions of Exchange. I’m looking forward to reading through this in a comfy chair, in front of the fireplace…
Download link: Technical Architecture of Exchange 2007
Microsoft Exchange Server 2007 introduces several architectural changes from previous versions of Exchange Server. This document provides descriptions and overviews of server roles, topologies, and the transport architecture for Exchange 2007.