OCS 2007 R2 has been released and there are quite a few questions about Installation, Migration, Features and Functions. To help you get acquainted to the product, here are some links to the most important information needed:

OCS 2007 R2 downloads
http://technet.microsoft.com/en-us/office/ocs/bb629431.aspx

Getting Started with Office Communications Server 2007 R2
http://technet.microsoft.com/en-us/library/dd441174(office.13).aspx

Capacity Planning
http://technet.microsoft.com/en-us/library/dd425159(office.13).aspx

Supported Migration Paths and Coexistence Scenarios
http://technet.microsoft.com/en-us/library/dd425356(office.13).aspx

Microsoft Office Communicator 2007 R2 Deployment Guide
http://www.microsoft.com/downloads/details.aspx?familyid=E5026127-101A-48D7-8683-C95F448329E3&displaylang=en

Microsoft Office Communications Server 2007 R2 Attendant Deployment Guide
http://www.microsoft.com/downloads/details.aspx?familyid=8CA31B00-96F3-42D7-9863-C44673F9C720&displaylang=en

You can also attend one of the Microsoft Partner Tech@Night events in either Zurich or Luzern to get an impression of what is possible.