As it stands, a developer makes three icons. One for the app list, one for the Marketplace listing (not 100% sure on this, but earlier posters seem to have confirmed this), and then one for the Start Screen. Like on the Start Screen I might make the app say 1Radio across the top, but on the app listing, it'll say 1R for short, to use an example. Of course, when I did it I just had it say 1R on each.