Telephony Integration Whitepaper and General UM stuff

 There is know loads of great material off the UC site as well as Technet

Here are some of the highlights

Integrating Telephony with Office Communications Server 2007 white paper

How to Build a Scalable and Available Unified Messaging System

Plus if you go to Building the Case there are some good case studies as well as other great references that will go to building your proposition