It looks like their "Sweat Parka" hoodie has a pocket made just for your DS, but since we can't read Japanese, and their English site is "beta only" right now, we don't know. The Zelda designs on it are pretty nifty though. Our favorite shirt is the "80s Videogamer" model. Simple with a message.
Although right now if forced to choose between a new Wii game and the shirt, we gotta go with the game.