In this post has been published a preview of SilveOS - a great and very practical demonstration of Silverlight features.
SilveOS.com is a Microsoft Silverlight based online virtual operating system. It is a website that simulates an operating system inside a web browser. SilveOS create the desktop environment of a modern operating system in your web browser which give you a familiar work interface that looks the same whether you’re working at your home computer, or remotely from a borrowed or public computer. User can Easily launch applications in your web browser without installation.