Eh... very mixed on this. Wouldn't saying "Trunk, open" to a voice-sensing car door be simpler than connecting your arms to a potentially hazardous series of wires and making unnecessary, awkward movements? Am I the only one worried about these sensors going berserk and seizing control of your bodily (or at least armular) functions?
I just can't see this being used practically. If you're too busy to play Guitar Hero and hold the guitar at the same time, you're too busy.