Larry Rayl a senior consultant at Catapult Systems has created and posted a nice set of SCOM 2012 Visio Stencils creating the possibility to even further customize your SCOM 2012 Visio designs.
There are some really specific Visio stencils in there which were not available out of the box in Visio or in the old Scom 2007 visio stencils.
A pretty cool addition to your standard toolkit if you ask me!
Check the original blog post here: http://blogs.catapultsystems.com/lrayl/archive/2012/11/13/system-center-2012-operations-manager-2012-stencil.aspx
Download them from SystemCenterCentral here: http://www.systemcentercentral.com/Downloads/DownloadsDetails/tabid/144/IndexID/96587/Default.aspx