I have just discovered the Si114x IR-sensing chip family
from Silicon Labs. They claim that the 3-leds version can be used for (close) 3D position tracking. Have a look at that video
. It features the evaluation board (SI1140DK) with 3 leds and X/Y/Z tracking. It's too bad that this board uses a C8051F800 MCU. If it came with an Atmel controller or as a breakout board I'd buy it immediately because it would ease the construction of a 3D interface quite a lot I guess.
The chip is ridiculously small (2 mm x 2 mm) and is sold only as a SMD component. Can a human being solder this ? I'd better find someone willing to make a breakout card for me...