I made a teardown video of this charger over a year ago and it's garnered me more hits than any other video I've ever created:
Recently I was contacted by a blogger who specializes in these kinds of chargers and he noted how the construction was ecellent, robust, and using the finest materials. Apple has really done their dilligence with this and it's no wonder they charge $20 for it.
I wonder if anyone knows how much wattage this thing can put out. Could you power a USB hard drive from it?