Slide on a pair of electrode-laden armbands, and suddenly all your sweet air-guitar licks are captured, finger by finger, without an instrument in sight. Sure, there are plenty of good reasons for this besides Guitar Hero.
Since Microsoft Research is so into "natural user interfaces", they showed off this one, called muscle-computer interface. It senses the movement of your extremities by tracing electrical activity within the muscles using a usually medical technique called electromyography. They've tried it in situations where users are engaged in physical exercise or have their hands full, like when bringing groceries to the car. They also connected it to Air Guitar Hero.
Natal is going to be really good for kicking and punching, but that camera array isn't set up for fine fretwork. I am not saying that this system is going to ever see the light of day, or that their ultimate purpose is ever-better air guitar. Still, it's nice to know that at least some of the $US9 billion Microsoft spends on its research division every year may solve this dilemma. [Muscle-Computer Interface]