It's a platform, a playbook, and a language for application architecture.

At a high level, that's how I think about our patterns & practices Application Architecture Guide and Application Architecture KB.

The work has become a focal point both internally and externally as a playbook for the Microsoft application platform.  It’s less of a guide, and more of a platform.  Essentially, we’ve framed out a durable, evolvable backdrop for application architecture that we can build on in terms of products, tooling, services and experiences.  I get daily/weekly mails from folks inside and outside the company that want to align their efforts with the frames and approach. 

I think of the frames as collection of hot spots.  The frames help cut through information overload and provide a common mental model.  They also help identify hot spots in architecture and design that are opportunities for improvement.  They also help map existing bodies of pattern work to relevant decisions that shape applications.

Here's a few data points that I think highlight the impact:

• As of today, we’re the #5 and #9 position in terms of downloads out of 7,328 projects.
• As of today, we're #9 and #16 in terms of page views out of 7,328 projects on CodePlex.
• Grady Booch says we’ve defined a language for describing our classes of applications.  See Grady Booch on the Microsoft Application Architecture Guide 2.0.