A colleague of mine recently published a 3 part series on the architecture and development of Rich Internet Applications using Silverlight 2.0.  If you are into Silverlight, this may be worth a look.

Abstract

This series of articles takes a look at the current state of RIA development leveraging Silverlight 2.0. The series will focus on the architecture of RIA's, the use of XAML for user interface layout and design, Windows Communication Foundation for Web Services, Visual Studio 2008 and Expression Blend for the design/development environment and Windows Server 2008/IIS 7 as the deployment environment.

http://blogs.msdn.com/bobfamiliar/archive/2008/04/04/rich-internet-applications-using-silverlight-2-0.aspx