The answer is yes, but I ran across a scenario that might save folks some time. If OCS is running in a Windows 2003 forest, and one or more domain controllers were upgraded to Windows 2008, OCS will not work correctly.
You can resolve the situation by running a forest prep. Page 8 of the Microsoft Office Communications Server 2007 Supportability details the exact steps.
Also, just a reminder that OCS 2007 RTM it is not supported on any version of Windows Server 2008. OCS R2 is supported on Windows Server 2008.
Update (Sept 2009): none of the OCS 2007 R2 components are supported on Windows 2008 R2.
