While browsing for chiptune software earlier i came across Matthew Applegate's blog, aka Pixelh8. He's a British composer best known for his custom-designed music software such as the Music Tech V2.0 for the Gameboy series of handheld systems. He recently announced that hes working on a project for Nintendo DS named The Pixelh8 Music Tech Master Stroke DS. The most recent post on his blog implies that the project is 95% done and he will release this software to the public once he finishes work on his third album.
Note: All sounds are produced via the on board sound chip and no samples or sample manipulation is used, this is a real time chip tune synth for the DS.