Games do not use the same soundsystem movies use but there are a lot of games that do take advantage of your surround speakers. Example: when playing Warcraft III the sound does 'move' with the characters, when they move to the left so does the sound and when they move out of direct sight the sound also moves from the front to the back-speakers. This really ads to the gameplay IMO.
Most music is stereo but the music is often mixed to four speakers (left to front-left and back-left, and right to front-right and back-right) and sometimes even the center speaker is used but this depends on your soundcard, speakers, drivers and the programs you use (RealOne only 'uses' my front-speakers, WMP both front and back and when using Linux the music also plays through my center speaker).