Here is the source to the TrustedApp media player sample I showed at PDC 2009. This sample requires the Silverlight 4 Beta which you can find here. This "trusted app" sample uses the new file system APIs, notification window APIs, windowing APIs, WebBrowser control, HTML Brush and Native integration. For Native Integration, this sample will take the current playlist and import/export to/from Excel (assuming Excel is on the system).
Note that this sample will look for MP3 files in your MyMusic directory and you will need at least a few MP3 files in there to see it running. Also note that if you have thousands of MP3 files, it may take a while on first load (post first load, the application will cache the list of files and it's much quicker).
Click on the image above to install and run this sample application.
Credits: this sample uses the TagLib Sharp library to extract meta-data from the media files.