We’ve implemented this – check out: http://blog.tunesbag.com/2009/01/share-your-tracksplaylists-with-friends.html

Simply use the “Share” feature to share a track with a friend and add some comment! Find all the details right here: http://blog.tunesbag.com/2009/01/share-your-tracksplaylists-with-friends.html

We can only agree, that would be cool, but there’re legal issues why this is not possible at the moment.