MoteDaemon is a neat Mac OS X app that gets a Wiimote talking to Flash via a socket server, with which these guys have written Wiinstrument.
I have written some Processing (0135 beta) code to work with MoteDaemon v0.5 to get it to talk to Processing too. Download my code here. It works pretty well, but isn’t happy when the nunchuk (and I assume the joypad) are attached – think the xml gets too big to parse at once. That can be fixed.
There are several other solutions to getting a wii to talk to Processing.
Cheers,
Dave