Microsoft has release CU5 for Lync 2010
Last week Microsoft quietly released CU5 for Lync 2010. The list of the various updates may be found below and the update includes a patch for mobility (if mobility is configured and deployed). I have installed the updates without any issue although the pool servers did require a reboot.
UPDATE: Lync Client and Server patches have been updated March 29th - the links below reflect the most current updates.
Lync Server 2010 build number is 4.0.7577.197
Lync Client build number is 4.0.7577.4087
Lync Group Chat build number is 4.0.7577.4071
Lync Attendee build number is 4.0.7577.254
Lync Attendant build number is 4.0.7577.253
Lync Phone Editions build number is 4.0.7577.4066