I understand that wiimote is fast and uses small bandwith because it has in-box 2D point tracking, which is good for games.
But at the same time it has it's the strongest limitation: it can process only 4 targets. It means that for head tracking or cursor tracking with many cameras (wiimotes) it could be the perfect 3D tracking platform.

But who needs a 3D tracking platform for 4 targets? There is no real use for that, except for the greatest idea of Wii gaming: buy 2 wiimotes, use one for tracking, one for gaming and have a lot of fun (for one people).

But the real questions is: how could we get 4+ targets out of wiimote?
Idea A: hack the hw and get the full raster CMOS signal and process it by PC. It's latency is going to be much worse than hw solution.
Idea B: design a small onboard SMD device, which processes up to 16 targets.

Look, it's possible (but at $500 for 1 camera and $5000 for a 8 camera system it's out of reach for many):
http://www.naturalpoint.com/optitrack/products/flex-v100/