I just got my hands on the new Tiger Woods 2010 for the Wii, which comes with a Wii Motion Plus. Well, I have it sitting on my dining table but I guess someone found out how to read the data off the Wii Motion Plus. Great timing although I have no use for it.
Ok so I, after much research, have been able to read the gyro data of the new wii motion plus peripheral with the arduino microcontroller. With this code and the code previously developed for the wii nunchuck (here), we are able to create a 6 DOF IMU for under $40. Thanks Nintendo! Best of all, everything is I2C so only 2 analog inputs (A4 and A5 needed for the wire library) are needed to read 6 sensors and no ADC conversion happens on the arduino board.