The new iPod Touch is so impossibly thin that in the race to get skinny, it had to get rid of a few features: specifically, the ambient light sensor that could adjust the brightness of the screen from the brightness of the room the iPod Touch was in. That's completely gone in the new iPod Touch.
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Source: http://feeds.gawker.com/~r/gizmodo/full/~3/kucW65mS1tY/the-new-ipod-touch-doesnt-have-an-ambient-light-sensor-because-its-too-thin-says-phil-schiller
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