Mod parent up. Note that this is using the camera on the Wiimote to sense the position (not the accelerometer). There are multiple advantages to this:
1) It's operating much faster than 60hz (much less latency than webcams).
2) It's already detecting the position of the brightest points (no additional image processing needed).
3) Since the Wiimote is wireless, you can easily position it anywhere.
4) Since it is Bluetooth, you can interface it easily with many devices.
5) You're not making the conductor hold the Wiimote.
All you'd need to do is to paint or cover the baton tip with IR retroreflective material, and perhaps add some IR LEDs around the Wiimote sensor.
This should make the baton tip stand out. You may still get several reflections, but software should be able to sort out which is the right one.
Alternately, you can use a baton with an IR LED in the tip, if the conductor is willing.
As far as output, I've got my own idea: the basic theme is to use 4 tactile devices (such as piezos) that indicate when the baton hits the respective quadrant (up/down/left/right, with some quadrants missing according to the time, and some modifications necessary for less common signatures). For seated musicians, you can use a chair pad. For standing ones, a floor pad might work better. Or you can also use various kinds of garments (glove, arm strap, belly strap, or any combination). However you wish to apply the 4 tactile devices, the system should be able to work with it. It may make sense to rotate the up/down/left/right "compass" 45 degrees either way for better sensitivity (for the chair or floor pads, for instance).
