The contest began in October 2006, and will run until at least October 2, 2011. They are offering a million dollars for a significant improvement in their Cinematch recommendation system.

Netflix will provide participants with a lot of anonymous rating data and the objective is to get a prediction accuracy bar that is 10% better than what Cinematch can do with the same data.

Participants must share their method and describe to the world how they achieved these results, in order to claim the money.

You don't even have to be a Netflix subscriber in order to enter.