via
Joystiq
Back in the golden days when we did a lot of gaming on PC, installations were known as "get pumped" time. You looked through the instruction booklet, you saw if you could wear the cloth map as a scarf, you'd watch the bar grow and, in short, get totally pumped. But PS3 owners today are, understandably, a little less jazzed when it happens to them.
MTV did a little digging to find out why some games need it and some games don't and the answers may surprise you. In short, different parts of a disc move at different speeds.