on my 7 foot wide screen. It can be a bit weird when you first point the controller at the screen. It doesn't show where you thought it would, but once your sensor is on screen, it's easy to flick around as our brains does the work for us.
In theory you could put two LEDs at the corners of the screen (or at whatever position makes the pointer show at the corner when you point it at the corner), but I'm not sure I would like it as much for general gaming like Mario Galaxy. as you would have to move your arm around a lot more.