I got a promotional email today from a new project called Kaggle. Somewhat related to Innocentive, this project aims to connect challenging problems with people that have the right set of skills to solve them. Kaggle is more specifically aiming to host prediction challenges and should appeal more to the data mining communities. For example, the site is currently hosting a challenge about HIV progression where problem solvers are giving a training dataset and asked to predict improvement in a patient's viral load.
I sent a few questions to Anthony Goldbloom (who works for Kaggle) to get a better idea of what the site is about: