Model View Controller
The ASP.NET MVC framework in now in Preview 3. If you are interested in testing out the framework, you can download it from here.
If your interested in learning more about Model-view-controller, there is a great article on Wikipedia here.
A Model-view-controller as a design pattern is not a new concept. Basically the concept is that the pattern seperates the business logic and user interface from each other, allowing for seperation of concerns (extreemly useful for unit-testing). MVC is not limited as a design pattern to web development, but the new ASP.NET MVC framework is.
From http://www.asp.net/mvc/ "ASP.NET MVC provides a framework that enables you to easily implement the model-view-controller (MVC) pattern for Web applications. This pattern lets you separate applications into loosely coupled, pluggable components for application design, processing logic, and display."
When I have more time, I'll publish additional MVC content.