http://blogs.technet.com/b/uspartner_ts2team/archive/2011/05/24/small-business-server-2011-with-server-2008-r2-sp1.aspx  Are you wondering if you should install the SP1 Service Pack for Server 2008 R2 on your SBS 2011 ? YES – it can and should be installed on SBS 2011 Standard edition. What about SBS 2011 Essentials ? – Great question – It is already part of Essentialsen-USTelligent Evolution Platform Developer Build (Build: 5.6.50428.7875)