The display assembly. (We did turn it on briefly, and it looks really nice!) On the right side are the three wireless antennas, and on the left side is the single display data cable.
Since the MacBook now uses a LED backlit LCD, there's no inverter cable. All data and power is transmitted through a single cable.
Apple has shaved about 50 grams off the weight of the display assembly compared to the one on the previous plastic MacBook.