Microsoft Office Communications Server 2007 R2 Group Chat Hotfix KB 969819
http://www.microsoft.com/downloads/details.aspx?displaylang=en&FamilyID=e5924bf9-b042-4c53-b4a6-79c7e5c9749b
This download contains updates for Microsoft Office Communications Server 2007 R2 Group Chat

• MgcAdmin.msp
• MgcClient.msp
• MgcServer.msp
• Microsoft Office Communications Server 2007 R2 Group Chat Add ins API.doc
• New Features in the Update for Office Communications Server 2007 R2 Group Chat.doc

• Update for Office Communications Server 2007 R2, Group Chat Server and Group Chat Compliance Servers: July 2009
  http://support.microsoft.com/kb/969819
• Description of the update for Office Communications Server 2007 R2, Group Chat Client: July 2009
  http://support.microsoft.com/kb/969818
• Description of the update for the Office Communications Server 2007 R2 Group Chat Administration Tool: July 2009
  http://support.microsoft.com/kb/969817