Yesterday the Lync Server product team was pleased to announce support for SQL Server 2008 R2 for all Lync Server databases! That's great news!
More information can be found on NextHop: http://blogs.technet.com/b/nexthop/archive/2011/04/20/lync-server-2010-support-for-sql-2008-r2.aspx
If you have any questions feel free to ask. Or sent you feedback/comments via the NextHop website (Leave Comment).