Neil Jansen is working on a toolhead exchange system that will enable you to quickly replace different tools on your 3d printer.
A small microprocessor like the ATTiny45 on a small circuit board is planned, for each tool. The hotend mosfet and thermistor circuit will be part of this board, rather than the RAMPS/Sanguinololu/Melzi, etc, and will communicate to it via serial over IRDA module (one on the ATC head / end-effector, and one on the tool). Power will be delivered to the board via pogo pins or via gold-plated contacts near the magnets.
