Really really small. Witness the new Motorola H5 in-ear microphone and speaker. Yes, it's a headset that fits completely inside your ear. It picks up your voice through your ear canal. To get around the obvious battery limitations of such a small device, Motorola includes a portable charging base to give a total of 7.5 hours of talk time (1.5 hours without the portable charger). And because it's right inside your ear, it eliminates external noise interference. Now if only I had a bluetooth phone...