Video - BMW Motorcycle Adaptive Headlight
A centrally-mounted movable xenon projection light shines up onto a diagonally-mounted mirror, illuminating the road ahead. As the nose of the bike pitches up and down with acceleration or braking, the projector light rotates in its housing to keep the beam level. This can compensate for loads too, so if your pillion passenger is exceptionally fat or you carry bricks in the panniers, the headlight will illuminate the road, not the sky. Basically the rotating light always keeps the beam level.
Things get more interesting if you check the "Adaptive Headlight" box (no word on cost). That adds a stepper motor which turns the mirror on an axis to compensate for lean angle. That also works in conjunction with the pitch compensation to ensure the bike's dynamic movement on the road doesn't affect the throw of the headlight.