http://technology.todaysbigthing.com/2009/08/07Infinite Mario AI
Infinite Mario Bros is a flash game that endlessly generates random levels. Right now there is a competition going on to program the best AI to play Infinite Mario. This is one of the entrys. The interesting part is that the AI is only aware of what's on the screen and it doesn't have a lot of time to compute, so having a faster computer will actually make it better at playing Mario.
More info on the Mario AI Competition
More info on this specific entry
And here's Infinite Mario Bros if you want to play, too