Check out the video with Brad Abrams about LOB applications with Silverlight 3. I’ve seen some at the PDC in LA last year which was promising.
“Come learn what it what it takes to building a data-intensive Silverlight application with the new set of features coming in Silverlight 3. You will learn how to write secure scalable N-tier applications in a way that as simple was writing 2-teir applications. Explore how improvements and futures in Silverlight are helping to enable rapid development for business applications and make your development process more productive”