I certainly do need to interact with Khan Academy more often, I need to brush up on my probabilities for technical interviews this summer, so I'll use that as a step into the product.
FWIW, having seen Salman Khan speak, it's hard not to be swept up with his cause. He's a man on a mission, and if anyone has the vision and charisma to pull off Khan Academy's goals, it's him.
I think an important distinction is also that the purpose of the math test graph is to specifically quantify prior learning (ie. it provides a reasonably realistic measurement of learning) -- this is not gamification necessarily. The badges are gamification. Our goal should be realistic and effective quantification of learning/improvement (passive feedback that generally increases intrinsic motivation), rather than implementing external motivators or artificial targets (which badges typically are).
FWIW, having seen Salman Khan speak, it's hard not to be swept up with his cause. He's a man on a mission, and if anyone has the vision and charisma to pull off Khan Academy's goals, it's him.