Emotiv Systems recently unveiled a brain/computer interface system with a helmet and software applications. The Project Epoc system can move objects based on a gamer's thoughts, reflect facial expressions, and respond to the excitement or calm the gamer mentally exerts.
Below is a video discussing and demonstrating Emotiv's new brain interface.
Tomorrow's Trends: Brain controlled computer games
Head Games: Video Controller Taps into Brain Waves: Scientific American
GDC 07: Project Epoc brings mind control to games - News at GameSpot