While the brakes may last the life of the car, some users dislike the black brake dust that accumulates on the rims. There are several third party brake pads the can significantly reduce the amount of brake dust. For the Model S:
Front AP1474 R4-S with counterweights (likely unnecessary)
Front AP1001 R4-S without counterweights
Rear AP 592.15 R4-S
Thanks go to LeonardV for figuring out the part numbers. See this Tesla thread for more details.