Just a quick heads-up: if up until now, iOS developers had to ask Apple to deal with fake scores and cheaters, an update now gives them the ability to deal with the issues themselves. Apple has also posted instructions on how developers can deal with such situations, referring them to the Managing Game Center Leaderboard Activity section in the iTunes Connect Developer Guide.
You can now view and manage the top 100 scores and usernames for all of your Game Center leaderboards. Protect your legitimate players by signing in to iTunes Connect to delete fake scores or block players that post fake scores. You can also restore scores and players within the same time period. To learn more, read the Managing Game Center Leaderboard Activity section in the iTunes Connect Developer Guide.