Microsoft TechNet Blogger, Sean Earp, has verified to me the Visio Stencils used by Microsoft’s User Assistance Teams for TechNet documentation are also compatible with Visio 2010.
Exchange Server 2007 Visio Stencils provide templates to create Visio drawings containing Exchange Server 2007 objects. These shapes include icons for Exchange 2007 server roles, networking, telephony and Unified Messaging objects, Active Directory and directory service objects, client computers and devices, and other Exchange organization elements.Geographic Map Shapes contain a set of shapes for creating "correct" geographic maps.Office Communications Server 2007 Visio Stencils contain icons to create your own diagrams of Office Communications Server topologies (server roles and components).Server Deployment Stencils for IT Professionals for creating diagrams for models of server deployments.Software & Database Shapes for creating software & database diagrams from the Express-G, Object Role Modeling (ORM), Jackson, and Real-Time Object-Oriented Modeling (ROOM) notations. (NOTE: Already included with Visio 2010 Professional.)
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