Motion Pong actually has been developed for the “Neoflash PSP Motion Kit”. It is a simple pong-game. The difference to other pong-games are the controls.You do not move the paddle with any keys, you just move it via the Motion Kit.That means you can move the paddle by tilting your PSP.

http://forums.qj.net/f-psp-development-forum-11/t-release-motion-pong-01-128095.html