We’ve received tips from a few different people about a new Bluetooth module that connects as a game cartridge for the Nintendo DS. This is a homebrew solution and not an official Nintendo add-on. The cartridge houses an ATmega168 microcontroller which provides the interface between the DS and a Roving Networks RN-41 bluetooth module.
They’ve provided a schematic for the device but we didn’t see any board artwork or pictures of the internals so you’re on your own for board layout. The libraries needed to use the bluetooth connection with homebrew software are up for download. This should provide a nice way to use the DS with a Bluetooth GPS module, or perhaps as a discrete Bluetooth sniffer and spoofer.