Last month I gave a Silverlight 4 keynote at the PDC conference. You can watch my keynote online here (my part of the keynote starts at the 53:30 mark in the video).
I showed off a number of fun demos during the keynote that highlighted some of new features coming in Silverlight 4. Today we posted the samples online (with code) so that you can download and run them locally on your own machines.
You can download the keynote demos here (source code + VS project file included with each sample).
Keynote Demos
Below are some details about each of the demos now available for download:
PhotoBooth Application
The PhotoBooth application demonstrates some of the fun things you can do with the new WebCam and Microphone support in Silverlight 4. It allows you to record videos and take photos within the browser – and then optionally apply effects to them (for example: the bulge effect below). For kicks you can publish a photo of any of the pictures to Twitter 
from ScottGu’s Blog more here