The Model-View-Controller (MVC) pattern is an architectural design principle that separates the components of a Web application. This separation gives you more control over the individual parts of the application, which lets you more easily develop, modify, and test them.
ASP.NET MVC is part of the ASP.NET framework. Developing an ASP.NET MVC application is an alternative to developing ASP.NET Web Forms pages; it does not replace the Web Forms model.
You can get the most up-to-date version of the ASP.NET MVC framework from the ASP.NET MVC download page. For information about what is new in this release of MVC, see ASP.NET MVC 3 on the ASP.NET web site.