The guide talks about the Fundamentals of Application Architecture and proposes Design Guidelines. It also discusses design and deployment patterns along with some cool guidelines while designing a layered approach.
Also check out the common type of architecture types(Web, Windows, Mobile) and their key design characteristics. There are also some cheat sheets at the end.
Overall, a 'must-read' guide if you plan to architect solutions around .NET
Download the Application Architecture Guide 2.0