The patterns & practices team provides guidance for many Microsoft technologies.
This project is not releated to Prism nor is it a replacement for Prism.
This project is about building interactive web applications using the latest web standards.
Prism is guidance and a framework for building WPF and Silverlight applications.
From the Project Silk home page, "Project Silk provides guidance for building cross-browser web applications with a focus on client-side interactivity. These applications take advantage of the latest web standards like HTML5, CSS3 and ECMAScript 5 along
with modern web technologies such as jQuery, Internet Explorer 9, and ASP.NET MVC3."
Have a nice day,