The classic video game Pong is implemented on a 5x7 LED screen worked into the dress. Two pixels on the right and left borders form the paddles; a single pixel is the "ball" moving back and forth.
At hip level, two retro-style game console controllers are plugged in to play the game. Every time a point is scored, the green score display at chest level blinks.
Update 22-Dec-2009: Take a look at a short video of the pong dress in action at a party.
Science fiction writers have, of course, led the way in thinking of ways that clothing can be so much more than mere fashion. In Philip K. Dick's 1977 novel A Scanner Darkly (recently released as a feature film), characters use a scramble suit to disguise themselves.
The scramble suit ... design consisted of a multifaceted quartz lens hooked up to a million and a half physiognomic fraction-representations of various people: men and women, children, with every variant encoded and then projected outward in all directions equally onto a superthin shroudlike membrane large enough to fit around an average human.
As the computer looped through its banks, it projected every conceivable eye color, hair color, shape and type of nose, formation of teeth, configuration of facial bone structure - the entire shroudlike membrane took on whatever physical characteristics were projected at any nanosecond, then switched to the next...
(Read more about PKD's scramble suit)
In recent years, futuristic clothing has moved from fiction to reality: