Microsoft Office Communications Server 2007 R2 Hotfix KB 968802 (6907.233)
http://www.microsoft.com/downloads/en/details.aspx?FamilyID=b3b02475-150c-41fa-844a-c10a517040f4

This cumulative update fixes the following issues:

• 2544768 An update is available that increases the maximum number of allowed access proxies in an access proxy array in Office Communications Server 2007 R2

Microsoft Office Communicator 2007 R2 Hotfix KB 2549042 (6907.233)
http://www.microsoft.com/downloads/en/details.aspx?FamilyID=515d6dba-4c6a-48bb-a06a-d99c5742676d

This cumulative update fixes the following issues:

• 2545288 An update is available to disable the extra presence information of a user in Office Communicator 2007 R2
• 2537249 Error messages when you enable logging in Office Communicator 2007 R2 after you install cumulative update 2291453

Microsoft Office Communications Server 2007 R2 Group Chat Hotfix KB 2549044
http://www.microsoft.com/download/en/details.aspx?id=12180