I read today on Brettjo Blog (http://blogs.technet.com/brettjo) an interesting post about Exchange Server 2007 templates for Visio.
You can get it here: http://www.microsoft.com/downloads/details.aspx?familyid=45f7ea49-ceb2-4b04-8d46-2b0ae5e10694&displaylang=en
Technorati : Exchange 2007, shapes, visio stencil
Del.icio.us : Exchange 2007, shapes, visio stencil