There is a great new feature available in SCCM 2012 Service Pack 1 (due for public release in Q1 of 2013)  that provides a fast “client notification” channel between server and the managed clients.  Read the full blog post from the product group here – http://blogs.technet.com/b/configmgrteam/archive/2012/09/27/fast-channel-for-system-management.aspx