Oh I forgot kinect 2 also has IR tracking.. @ 512 × 424 resolution. ..not entirely sure what advantage this would provide...
It's not IR tracking, it's an active IR camera.
Basically if you switch off the 'special kinect IR light source' and use a standard IR lightsource then you will get an IR iluminated image aka an active IR camera (or 'nightvision').
I assume this would work well for video chat etc in zero-light environments or "something"? (the 512x424 resolution for the image is a bit weird, as the raw image should be far higher resolution)