https://marco.org/2010/09/09/game-center-should-allow-non-game-ios-apps-to
Game Center should allow non-game iOS apps to register for achievements and leaderboards. Think about it: Largest Dropbox File, Most TextExpander Time Saved, Longest iStat Uptime, Most LoseIt Pounds Lost This Week.
— David Chartier nails a great idea. I’d love to make Game Center-shareable achievements in Instapaper, but I don’t think there’s any chance that Apple would approve it, even after today’s improvements.