Retail Rock Band mic not actually Wii-compatible

Wii Rock Band continues to surround itself and everything around it with an air of irresistible mystery, even after confirmation of its release. Last week, we received an early clue to the game's existence from the packaging for a cross-platform Rock Band microphone-- or so we thought. Turns out, the microphone isn't actually Wii-compatible, and the mention of Wii on the case was an error. In other words, it was just a coincidence that a Rock Band microphone was marked as working with the Wii a week before we officially heard about the game.

Now, on to the next mystery: why the hell do only certain USB microphones work with the Wii? They're USB microphones.