Yes, there are quite a few motion sensors which do that, including theramin-to-MIDI (30cm range) (doepfer electronics, for example), video-tracking (range of several meters) (CMUcam, etc.), acoustic rangefinders (devantech, etc.) and light (up to 3 meters) (or infrared) sensors. A couple of years ago, I needed a large number of motions sensors for almost no money, so I used LDR’s to pick up the reflections of peoples clothes and bodies. I was using a 32-input CV-to-MIDI interface, but you could just as well wire an LDR directly to a game-port or a hacked Joystick. The end result was effective from 0 to 3 meters (depending on ambient light, clothing and skin-color) and looked like the photos on this page: http://www.magpai.net/webes/pieces/polyurethane/index.html
You could do the same thing with infrared without the need for the visual light I was using, as long as you have a good infrared emitter.