CU6 for OCS 2007 R2 was released a couple of weeks ago. OCS 2007 R2 CU6
The simplest way of installing is to download and run the ServerUpdateInstaller. This will install all of the needed patches to your OCS server.
Unfortunately there is a problem that you might encounter when doing so. The FrontEnd service will not start and you will se this in the eventlog. “The Office Communications Server Front-End service terminated with service-specific error 3287186749 (0xC3EE7D3D).”. Reason is that serverinstaller does not contain all updates needed. The FrontEnd server patch needs an updated database to run correctly.
What you need to do is to ununstall KB983472 and then install the OCS2009-DBUpgrade.msi to upgrade the databases used by OCS.
OCS2009-DBUpgrade.msi is found in KB 2032834, Description of the cumulative update package for Office Communications Server 2007 R2 database: July, 2010
After databases have been upgraded you can reinstall KB983472 or simply run serverinstaller again and since databases are updated, the OCS FrontEnd service will start normally.