Did you know that Webcams and microphones are now accessible from Silverlight 4 applications?
Developers can enable video and audio sharing for real-time collaboration and interactive multimedia applications.
This video (and code samples by Tim Heuer demonstrates how to utilize a user's web camera and microphone attached to their computer via the browser. This demonstrates the basics of the core API for capturing the audio/video.
Check it out at: http://www.silverlight.net/learn/videos/silverlight-4-beta-videos/access-web-camera-microphone/