Mike Taulty has posted an interesting sample showing 12 WMV media elements  all running in the same "WPF/E"-based web page.  Imagine being able to watch sporting events streamed in multiple video windows, mouse over a window and get the main screen view.

The uses for this technology are endless.  Imagine a device such as a Crestron-like touch screen control that has live previews of video across multiple channels.  Press the video feed you want and your TV switches.  It might be time to start playing with "WPF/E" inside Media Center's SDK too... ;)