Thanks for Microsoft Press, there are two free e-books for download for June. :)  The URLs are live from June 17-24.  Download the book before it expires…

Programming for Unified Communications with Microsoft Office Communications Server 2007 R2

By Rui Maximo, Kurt De Ding, Vishwa Ranjan, Chris Mayo, Oscar Newkerk, and the Microsoft OCS team

Link is: http://csna01.libredigital.com/?urrs4gt63d

Microsoft Office Communications Server 2007 R2 Resource Kit

By Rui Maximo, Rick Kingslan, Rajesh Ramanathan, and Nirav Kamdar with the Microsoft Office Communications Server Team

Link is:  http://csna01.libredigital.com/?urws8un4p7