The commercial that launched the Mac aired only once, during Super Bowl XVIII, and it is credited for starting the Super Bowl creative commercial competition among ad agencies. It is considered to be one of the most innovative commercials of all time, on a number of levels. Advertising Age selected it as the "Commercial of the Decade."
It has its own Wikipedia entry here. Wired Magazine online gives an interesting history of it here.
But you really need to watch it here.
- Hap