answer:the reason for the plastic is because the metal gives bad reception against the antennas, that’s why you see a lot of unhappy macbook pro people because their antennas are behind the aluminum casing and they get less signal than the plastic macbook owners. it doesn’t act to boost it, instead the plastic is there so that it gets less [bad] interference. as for the 2nd gen ipod touch, that isn’t bluetooth, that is the nike + adapter