After what seems like eons, Microsoft have finally announced support for OCS 2007 R2 running on Windows Server 2008 R2.
There are a number of steps to run through before installing OCS 2007 R2 on top of Server 2008 R2. Note that it’s not supported to upgrade an existing Windows 2008 Server already running OCS 2007 to R2.
Note also, that group chat is not supported in a 2008 R2 DOMAIN.
There are a couple of relevant KB articles:
Office Communications Server 2007 R2, OCS 2007 or LCS 2005 does not work correctly after you upgrade to Windows Server 2008 R2 http://support.microsoft.com/kb/982020/
Supportability is available for Office Communications Server 2007 R2 member server role on a Windows Server 2008 R2 operating system http://support.microsoft.com/kb/982021/
The first article is about the domain, and problems that can occur with OCS when upgrading a domain controller in the existing domain to Server 2008 R2.
