This includes fixes for most major Lync server 2010 roles including the administrative tools, the core components, and the mobility service which contains an engineering solution to the IIM Filtering and Push Notification as described here http://support.microsoft.com/kb/2664650
- Download: http://www.microsoft.com/download/en/details.aspx?id=11551
- Knowledge Base Article KB 2493736: http://support.microsoft.com/kb/2493736
As usual the cumulative installer is available in the LyncServerUpdateInstaller.exe download.
The associated CU5 Lync Client updates are also available:
A list of all the server role and client updates for Lync CU5 is listed here: Cumulative update for Lync 2010: February 2012.