One of the new features in TFS 2010 is the Layer Diagram. This allows you to draw a graph with the different layers inside your application and define their dependencies. Afterwards you can link source elements(projects, files,…) to it. What makes this feature really nice, is that you can let Visual Studio validate if the dependencies as defined in the layer diagram are followed by your code.
To enable this feature on your build server, right click on your build definition, select Edit Build Definition. Go to the Process tab and add the following MSBuild argument to the MS Build Arguments parameter in the Advanced node:
1: /p:ValidateArchitecture=true
More information here: http://blogs.msdn.com/ukvsts/archive/2010/03/11/validating-your-architecture-during-a-build.aspx.