Aspect Ratio

 At 1024x768 resolution, the iPad's display has an aspect ratio of 4:3. The trend these days actually is going towards 16:9 and represents a step back. However, given the orientation of the Apple logo on the back, the iPad is probably meant to be primarily to be used in portrait mode and a 9:16 aspect ratio would have been too narrow for the screen.

Curiously, as Lonely Sandwich pointed out in the graphics above, the iPad in portrait mode is equivalent in aspect ratio to two iPhone screens stacked in landscape mode. This definitely makes for some interesting possibilities...