GBA-brained Mo-Bot takes orders via bluetooth
TeamKNOx a tribe of Japanese mobile console modders have used the XPort 2.0 kit set to build a GBA robot which they issue commands to via a bluetooth enabled smartphone.
They also have pictures confirming the kit working on the DS as well as the GBA and make special mention of the DS's suitability for such applications because of it's WiFi capability.
Anyone else ever tamper with the XPort and a GBA? Kits are a great way to get started and they can save you substantial ass-pain when getting started.