LittleBigPlanet: Over 650,000 levels and 1,935,000 online players
PSU has some promising data on LittleBigPlanet. The game has been around for over 4 months now and over 650,000 levels have been created in total.
The game has a total of 1,935,000 online players, with an average of 35,373 levels delivered each week.
Additionally, they estimate a new level is uploaded every 17 seconds! These figures are astonishing and an amazing achievement for Media Molecule and Sony.