I really hope they lose 404, or mocap, its a bit of a waste. Just add an extra accelerometer and a few fiducials across the device, it would accomplish the same thing and possibly more. I don't like it, they had a chance to do something great, and they made that thing that looks like a scepter. I feel like this is something my sorc should have held back in the D2 days.
Most likely so it knows which way is North. Possibly for tracking and integrating true direction into games, because they're crazy like that.