Grab it here: http://www.microsoft.com/en-us/download/details.aspx?id=36517

Biggest changes are Call/Conversation History, Media Resiliency (automatic reconnection) and OS X Yosemite support.

• Update enables users to view call history in Lync for Mac 2011
• Update for Lync for Mac 2011 enables users to store conversation history on an Exchange server
• Location is not displayed in Lync for Mac 2011 when users join a wireless network
• Error “One or more selected contacts cannot receive your calls” when you forward calls in Lync for Mac 2011
• Delegation relationship is broken after a delegate signs in to Lync for Mac 2011
• Computer shutdown is not processed when Lync for Mac 2011 is running
• Update implements media resiliency mode in Lync for Mac 2011
• Dial pad disappears when a user who is not enabled for EV joins a video conference or a video call in Lync for Mac 2011
• Update enables users to interact with a contact from the call history in Lync for Mac 2011