MSDN Magazine : Silverlight 2 Web Parts for SharePoint

Silverlight and SharePoint provide a simple, yet powerful, infrastructure for building intranet and extranet applications with sophisticated user interface designs and interactions.

In the November 2008 issue of MSDN Magazine, Steve Fox and Paul Stubbs demonstrate how to build a SharePoint Web Part as a wrapper for a Silverlight application.
MSDN Magazine : Silverlight 2 Web Parts for SharePoint