Wow. Just had a look at a DNR TV show (http://www.dnrtv.com/default.aspx?showNum=115) by Bill Hollis where he illustrates how to build great user experiences using WPF.
This is quite a mind shift from my usual black and white screens (and some will know me for my orange ones :)) using Microsoft Sans Serif fonts. The combination of layout, animations, design and patterns is mind blowing. You need to see it to realize how far technology has come from traditoiinal windows forms and ASP.NET forms.
You simply cannot purely focus on integration and business logic anymore. We will need to consider the UI integration and patterns as well. I think the MVVM patterns will be a good fit here as well as the powerful WPF routing capabilities and the power of layouts (especially list boxes).
Will seriously need to consider these kind of principles in all new projects going forward using Silverlight or WPF.