Thanks to Tad at AIS for bringing this one to my attention. We have some early experience in combining Silverlight and SharePoint, based on the 1.1 alpha work we did back in July as well as some 1.0 work since then. We did only the most basic integration early on, though. We're working on combining Silverlight 2 and MOSS/WSS (within AIS and on the revamp of my own site), so this couldn't have come at a better time.
Now Microsoft has come up with a set of samples and examples for combining SharePoint and Silverlight 2. From Microsoft's site: 
The Silverlight Blueprint for SharePoint is source code and guidance for developers describing how to use Microsoft Silverlight and Microsoft SharePoint Products and Technologies together in business applications and Internet Web sites. SharePoint applications that use Web Parts can now be built using Silverlight user interface elements. This capability enables a fresh look at data exposed through SharePoint Products and Technologies using the modern graphics capability in Silverlight.
Six application component samples are included in the kit to get you started:
- A simple “hello, world” sample showing Silverlight in a Web part.
- A Silverlight slider control as a SharePoint custom field type.
- A navigation control.
- A Colleague Viewer that uses lookups in Active Directory by using Windows Communication Foundation.
- A Silverlight picture viewer from a SharePoint picture library.
- A visual how-to center, created in Silverlight and based on a SharePoint list, for viewing videos.
You can get the blueprint here. Best of all, it's Silverlight 2 code!