This is the greatest web service ever.
I’ve seen similar approaches to spam detection, but I wonder if they really understand human nature well enough to pull it off. Don’t you have to check the answers to ensure no-one just wrote a script to auto-respond to earn 0.0001p?
Anyway, hats off to Amazon for lateral thinking – this is the technical equivalent of working around the bugs in ViaVoice by adopting a small child and teaching them to touch-type.