Today, at the VoiceCon 2006 conference, Cisco Systems and Microsoft Corp. announced they are working together to provide collaborative real-time capabilities for businesses through the integration of Microsoft® Office Communicator 2005 and the open Session Initiation Protocol (SIP)-based Microsoft Office Live Communications Server 2005 with the new SIP-based Cisco Unified Communications system.

See the full announcement at the Cisco site at:
http://newsroom.cisco.com/dlls/2006/prod_030606c.html

Or at the Microsoft site at:
http://www.microsoft.com/presspass/press/2006/mar06/03-06CiscoRTBCPR.mspx