Folks,

I work with a company that develops a similar device.  It does not read emotions or thoughts.  It reads electrical impulses across the skin that trigger when certain brain waves trigger.  Some of these brain waves are associated with emotions.

Most of the functions for emotiv are unintentional, not able to be controlled very well.  In live demos the company recommends it more for atmospheric elements such as triggering attacks from in-game monsters when a user is nervous.  They demonstrated it with a Harry Potter game, and it always took a few seconds to get any of the direct triggers to do anything inside the game.

I own a similar system called Brainfingers, marketed by OCZ as the Neural Impulse Actuator.   http://www.youtube.com/watch?v=BKd_AJUUT7Q  It has directly controlled triggers along with many of the same indirect triggers.  The direct triggers are controlled by moving facial muscles.

I use it for gaming.  It frees the hands for other functions, and most 3D games have a lot of things to do such as movement, triggering special weapons and functions, etc.  As a trigger, the facial muscle functions are faster than clicking a mouse, which was proven in tests with the air force.

Right now the only brain interface devices that actually read movement signals from the brain, things like telling your hand to move, require surgery and implanted connections to the brain.