One of the things that many people have asked for over the years with ASP.NET is built-in support for developing web applications using a model-view-controller (MVC) based architecture.

Here are two interesting links:

ScottGu - http://weblogs.asp.net/scottgu/archive/2007/10/14/asp-net-mvc-framework.aspx

Scott Hanselman - http://www.hanselman.com/blog/ScottGuMVCPresentationAndScottHaScreencastFromALTNETConference.aspx