Silverlight is a powerful development platform for creating engaging, interactive user
experiences for web, desktop, and mobile applications. Integrating Silverlight RIAs in
SharePoint 2010 offers amazing opportunities to combine the power and flexibility
offered by SharePoint. It is easy to create great user experiences when you have a step-
by-step guide to implement Silverlight 4 applications on SharePoint 2010 sites.

http://go.microsoft.com/?linkid=9742696