Office Communicator Server 2007 R2 on windows 2008 R2?

 At the step 2 of the installation, its going to check for components, then the installation will bring you back to the same page in an endless loops, even after checking all the pre-requisites and best practice on Microsoft website.

However, there has been a fix available for a little over a year now: http://support.microsoft.com/kb/982021

The best practices for OCS is to stay on windows 2008 SP1 or windows 2003 32 bits. The 64 bits version for windows 2008 and the 32 bits version for windows 2003.

Of course one of the best practices is not to try products that have been released before the integration of new Operating  Systems, but sometimes, for the sakes of intellectual curiosity, the human mind needs to know if this can be achieved.