Although the call for this competition has been out for a while on KDnuggets.com, today is the day when the data and the task description are released. This data mining competition is aimed at students. The prizes probably might not sound that attractive to student ("participation in the KDD 2008, the world's largest international conference for "Knowledge Discovery and Data Mining" (August 24-27, 2008 in Las Vegas)", so I'd say the real prize is cracking the problem and winning!
An interesting related story that I recently heard from Chris Volinsky from the Belkor team (who is currently in first place) is the high level of collaboration that competing teams have been exhibiting during the Netflix Prize. Although you'd think the $1 million would be a sufficient incentive for not sharing, it turns out that the fun of the challenge leads teams to collaborate and share ideas! You can see some of this collaboration on the NetflixPrize Forum.