Attention Macintosh users put down your one button mouse for a minute, for now you can enjoy some the UC experience your Windows counterparts already do.

Microsoft Messenger for Mac 7 is now available, besides just being able to  connect to Windows Live service, Microsoft Messenger allows you to connect Office Communications Server! 

More Information: http://www.microsoft.com/mac/products/messenger/default.mspx 
Download: http://www.microsoft.com/mac/downloads.mspx?pid=Mactopia_Messenger