Post de un empleado de Valve. Basicamente que si tienes más de 5000 MMR estes atento a las notificaciones.
The DOTA team is working on official leaderboards. The leaderboards will be based on solo MMR, and there will be some eligibility requirements based on number of lifetime games played, as well as number of solo ranked games played within a recent time period. We're still finalizing the details and will share them when the first leaderboard is posted.
We sent in-client notifications to about a thousand players requesting official player data that will appear on the leaderboards. Unfortunately, many players who are eligible have not yet responded to this notification. Before we post the first leaderboard, we would like to have more players with official player information on file.
Please spread the word: If your solo MMR is high (>5000 or so) and you have played several solo ranked games recently, check your in-client notifications. If you have a pending request for official player information, please submit it!
If you didn't receive a notification, don't worry! If, at any time in the future, you are within reach of a leaderboard and meet the eligibility requirements, we will make it possible for you to submit your information and appear on the leaderboard.
http://dev.dota2.com/showthread.php?t=130209