Ethos has updated his Gameboy Emulator for the Nintendo DS, heres what he posted:

Here is another demo of the emulator. As you can see it runs a lot faster than the previous demo. The biggest problem right now is in CGB double speed mode. The emulator slows to a crawl. Oh well. Sorry about the lack of work, since I got a promotion at work, and also got engaged! Also note the second demo has a save feature (press start in game). It will save only to a non-commercial GBA cart, with any recent DS homebrew program on it.

Download Here --> http://nintendo-ds.dcemu.co.uk/gbemuds.shtml

Official Site --> http://ethos.oddigytitanium.com/