I already saw this at the french robotic cup in 1999, here is Your chance to buy a mature kit: the Xport 2.0. You can now create amazing robot creations with a Game Boy and some LEGOs....

The new Xport 2.0 turns the Game Boy Advance (GBA) into a powerful embedded development system. 

• 4 closed-loop back-EMF motor controllers
• 16 digital sensor inputs
• 8 analog sensor inputs
• In-system NiCd, NiMH battery charger
• Battery voltage monitor
• Comprehensive open-source software
• Optional Bluetooth and other accessories
  

Combine with a game boy advance, you have among other things a system:

• Programmable in C or C++
• PCM sound
• 240x160 TFT color LCD
• Powerful 32-bit RISC CPU