Competitive Self-Play
I imagine this is the way we get to "true AI", or AI indistinguishable from our own. We train it with a simple virtual environment, that we can gradually increase the complexity of, until it mimics our own. Then we can download the AI into a robot. Boom, it's that easy :P<p>One interesting outcome of this type of AI is that no one knows what the robot's thinking, since no person designed its brain. The brain evolved, just like ours did (but over such a shorter period of real time).