Not everything inside the Wii, or its motion-sensing controls, is owned by Nintendo. There's a lot of stuff in there that belongs to other companies, and those components are making these other companies very rich. In particular, two companies that have parts in the Wiimote and nunchuk, the US-based Analog Devices and Italian-French company STMicroelectronics. Think about it, Nintendo may have 10 million Wiis out there, but there are far more Wiimotes and nunchuks.
Analog Devices had to convert one of its plants into a fully-dedicated Wiimote sensor facility. STMicroelectronics is in the process of increasing sensor production near Milan -- hmm, they're the ones responsible for the sensor in the nunchuk. Wonder if they're to blame for the nunchuk shortage of '06? With Nintendo raising it's Wii shipping estimate to 16.5 million by the end of their fiscal year next March, those parts companies better not stop the flow. It's still hard enough getting the console as is.