An Infra-Red Leash for an Electronic Dog?

One of the things I intend to implement is the ability for this robot to follow me or a target I designate. I was thinking about how I could implement this feature and thought I would just record my thoughts so far.

I had been planning on cannibalizing a WII remote at some point for its infra red camera. I did some looking around on the internet today and I found another useful Intructables project on how to extract the Wi Remote's infrared camera and the hardware that monitors it and connect it to an Arduino.  It then cranks out the x,y coordinates of the four strongest infrared sources it sees and makes them available to the Arduino.

One of the experiments I need to perform is to see if I can use this camera to track an infrared LED I could then wear one and have the robot follow me by attempting to center the x coordinate by rotating its body as it moved.

The distance from the center point of the display in y would be proportional to the distance from the target. If I had some idea as to the average distance from the floor the LED was mounted on the target I may even be able to calculate distance. At close range the LED may go outside the field of view anyway in which case you would have to assume you had reached the target.

I have not thought much yet about where on the robot to mount it. Would there be any advantage to placing it inside the head which can move up and down in the Y axis?

This camera has been used to create simple electronic whiteboards as well.  Perhaps I could also use it as an input device for drawing in the air or on a white board as well. Another interesting fact I did not know is that WII remotes use bluetooth to communicate and can be paired with any laptop with bluetooth build in. Bluetooth is not really an option for me since I don't want to add another radio if I can avoid it. I am already planning on using WIFI for remote control and internet access.