You Rock Guitar is a company that has made an electronic giuitar that is fully functional both as an actual guitar instrument, and can be used with the music genre video games. This is acheived by switching between modes via a control panel; when in actual guitar mode, you play the instrument just as you would, and in game mode, you'll press the corresponding colored buttons to play the notes on the screen, and pluck and string to strum.
The guitar runs wireless of batteries, though he wasn't certain on a definite life. The neck will detach, and the head will further detach from that, to help transfer the instrument to and fro.
YouTube Demonstration video: http://www.youtube.com/watch?v=-s217m6wLXU