The docs answer a few questions about the controller: namely that it’ll rely on alkaline battery power (in the form of two AA batteries), will contain 6KB of “non-volatile” memory (possibly for the controller’s internal speaker, though it’s not known for certain), and will talk to the console on the 2.4GHz band, via Bluetooth. There’s a bunch more details over at IGN, including info on the controller’s LEDs and the receiver hardware.
Personally, I’m a little concerned about the use of the 2.4GHz band, which is already pretty heavily saturated with Wi-Fi and many cordless phone models. With this much noise on the frequency, could microwaving up a bowl of macaroni and cheese (a favorite gamer pastime) wreak havoc with your friend playing Zelda ? Cries of “no fair” and “lamer” will no doubt echo throughout the realm.