Enter Musicast, an $18.00 Universal application that opens your playlists to the world. Once you launch Musicast you see a list of your playlists (both smart and not so smart). You can pick and choose which you would like to make publicly available and that's it. Now your Mac has been transformed into a music streaming machine (though imagine an internet connection is required for this to work).
I wonder if this is breaking any silly copyright laws.