I seem to remember Steve Jobs saying during the iMac G4 intro that turing the optical drive on it's side makes it slower... yet that's how the drives are now...
Link: http://www.youtube.com/watch?v=FYRY-PCKdDg (right around the 2:00 mark)
Link: http://www.youtube.com/watch?v=FYRY-PCKdDg (right around the 2:00 mark)