I have worked with Rui Maximo, Jochen Kunert and many others in and around
the product team to build a book to help provide background and tips for OCS
2007. There are sample chapters available on the web at:

http://www.microsoft.com/downloads/details.aspx?FamilyID=407a3e40-350a-4e3d-b60e-c9505668b231&DisplayLang=en

I wrote chapter 4 - Basic IM and Presence Scenario and it contains a simple
overview of the usage scenarios and then digs into the details of the
protocol, authentication, message flow and discovery and routing mechanisms
that were involved. I hope that you'll find it enlightening in its technical
depth, but I'd love to hear your feedback. You can reach me directly at
jbuch@microsoft.com.

Please take a look at the chapters (quotes from some of your favorite
support, consultant and product group folks as well) and let us know what you
liked and didn't like. The book is currently marketed as available on
12/12/2007 and pre-orders are already possible through most book sellers on
the web.

Overview

Download your preview chapters from Microsoft Office Communications Server
2007 Resource Kit, the definitive resource for deploying and administering
Office Communications Server (OCS) 2007. Direct from the OCS Team, this
reference will deliver in-depth technical guidance and expertise—plus tools,
scripts, and more on CD. The preview chapters are uncorrected manuscript, for
early preview, are subject to change prior to release, and are are provided
without any express, statutory, or implied warranties. The preview chapters
available to download are:

Chapter 3: Infrastructure and Security Considerations

Chapter 4: Basic IM and Presence Scenario

Chapter 9: Remote Call Control Scenario

For more information and to purchase the book, go to
http://www.microsoft.com/MSPress/books/10482.aspx

About the Authors
Jeremy Buch: Jeremy was a Senior Development Lead for the Microsoft Office
Communications Server SIP protocol stack and developed conferencing, network
protocols and secure federation technology for over 8 years. Jeremy changed
roles in 2006 and is currently working for Microsoft Virtual Earth in
Boulder, Colorado as a senior development lead for 3D Urban Modeling.

Jochen Kunert: Jochen has extensive experience in integrating VoIP software
applications into existing enterprise telephone environments. He is now a
senior program manager in the Office Communications Server Customer
Experience Team in Redmond, Washington.

Rui Maximo: Rui is a lead program manager in the Unified Communications
Group. He has worked on various aspects of Live Communications Server 2003,
2005, SP1 and Office Communications Server 2007 from migration, topologies,
Active Directory schema extensions, management to VoIP and Communicator Web
Access. With 11 years of experience at Microsoft, Rui has worked in diverse
roles and various products (NT 4.0 Option Pack, Windows 2000, Windows XP,
Smartphone 2002, Pocket PC 2002, MIIS 2002).