DS has just saturated the market so much in Japan, that hardware is just pathetic now. I mean gosh Nintendo has to realize by now that the DS Lite is at its end, and if DS sales want to stay up, they need another revision or a new handheld in Japan. I mean it's pretty obvious.
Otherwise PSP has taken over, somewhat, from where DS has dropped, and Wii stays steady. Everything else is well pathetic.