The papers of the winners of the Netflix movie recommendation competition are here
Yahoo! Labs hosted the KDD Cup 2011 contest, which included two music rating prediction tracks and the top performers are here http://kddcup.yahoo.com/leaderboard.php. The final champions of both tracks were National Taiwan University who said they learned a lot from the Netflix winners papers and did implemented some of their algorithms. They also researched many other mature solutions, the details can be found at http://kddcup.yahoo.com/workshop.php.
Some of those methods are included in the Apache top level project Mahout which is dedicated to data mining and machine learning. Check out http://mahout.apache.org/, there are great user resources and many more goodies to learn and master. It seems there is still little awareness of this prize in the Mahout community. It would be beneficial to both sides to unite the two groups of great talents.