Exchange TechNet Wiki page you find the various posters and Visio stencils that exist for Exchange 2007 and 2010.
Exchange 2007 Hub Transport Role Architecture - RTM (PDF)
Exchange 2007 Hub Transport Role Architecture - SP1 (PDF)
Server Posterpedia is a Windows Store app designed for Windows 8 and Windows RT that brings graphical content together with content from TechNet and MSDN. It enables you to learn about Microsoft technologies
by providing deep links to Microsoft content from within a Windows Store app.
Server Posterpedia is updated frequently with new content, so be sure to download any app updates when you’re notified.
If you’re running Windows 8, you can get this app from the Windows Store:
If you’re not running Windows 8 yet, check out this video that illustrates the app’s features and functionality:
When are the Exchange 2010 stencils going to be available?