Exchange 2007 deployment documentation
Just noticed these documents posted at the Microsoft Download Center:
Deploying a complex Exchange Server 2007 organization
As its name implies, a complex Exchange organization represents the most intricate topology into which Exchange 2007 is deployed. Of the four defined organization models for Exchange 2007 (simple, standard, large, and complex), the complex Exchange organization is the only model that includes multiple Active Directory directory service forests or the use of synchronization technology. This document will provide the planning and deployment information you need to get your complex Exchange 2007 organization up and running. Get it here.
Deploying a large Exchange 2007 organization
Of the four defined organization models for Exchange 2007 (simple, standard, large, and complex), the large Exchange organization is the largest organization model that can be deployed in a single Active Directory directory service forest environment. This document will provide the planning and deployment information you need to get your large Exchange 2007 organization up and running. Get it here.