Silverlight Multimedia Tool/Editor/Movie Maker

We need a multimedia tool made in Microsoft's Silverlight (it's their replacement to flash and is currently in alpha) Basic concept is to take audio, video and images and create a time line edit capability where you can create a multimedia presentation along with some transition effects. The time line should have a video track and an audio track, the ability to overlay text and images with the ability to set color(of the text), opacity of text and images, and fade in/fade out transition effects and some other basic transition effects. This will be based on a media library which we have already built that is provided by a web service, when the web service is queried it will return results as URL's that the files can be downloaded from. The final result should be saved via a web service as xaml and be able to be loaded and watched.