The OCS 2007 R2 binaries were recently released for public download. The table below is a compiled list of currently available R2 downloads:

Title

Microsoft Office Communications Server 2007 R2 Trial Download

Microsoft Office Communicator 2007 R2 Trial Download

Microsoft Office Communications Server 2007 R2  Attendant

Office Communicator Phone Edition (2007 R2)

Microsoft Office Communicator Mobile 2007 R2 - Pocket PC

Microsoft Office Communicator Mobile 2007 R2 - Smartphone

Microsoft Unified Communications Managed API 2.0 SDK (32 bit)

Microsoft Unified Communications Managed API 2.0 SDK (64-bit)

Microsoft Office Communications Server 2007 R2 UCMA 2.0 Speech Language Packs

Microsoft Office Communications Server 2007 R2 Group Chat server

Microsoft Office Communications Server 2007 R2 Group Chat client

Microsoft Office Communications Server 2007 R2, Group Chat Administration Tool

Conferencing Add-in for Microsoft Office Outlook

Microsoft Office Live Meeting 2007 client

Microsoft Office Communications Server 2007 R2 Group Policy Documentation

Microsoft Office Communications Server 2007 R2 SDK