A leaked update for Google Play Services has strongly hinted that Google Play Games, a new platform Google has been working on, will be unveiled at I/O event.
Trusted source Android Police, revealed the Google Play Services v3.1.36 update, which is a significant update over the 3.0.27 which is in use right now, and is slowly coming to devices.
Sometime back, Android Police found clues in the Glass Companion app, My Glass which suggested that Google was developing a gaming product with a social sense. It would have shared characteristics with the Game Center on the iOS platform.

Google Play Services v3.1.36 has detailed some of the features to be expected from Google play Games. Some of the supposed features of Play Games will be to allow users to sync the games they have saved, as well as compete with friends for titles and high scores. Users will have the ability to make invites to friends to play some certain games, as they respond to invitations passed out to them. One other interesting feature is match-maker, where Play Games will select players automatically for some games.
The social elements of the application will be serviced by Google+. This was expected. With the integration, players will compete with friends in different games, and the social network will handle identification and notification details. As Google+ lets you choose what you share in public, the same feature will be extended to the app. Your performances, which you can share or keep discreet, will be recorded on Leaderboards, sorted by time in three settings- today, week, all time.

The icon badges imply that developers will have the chance to include Play Games support in their titles. They would be indicative of whether a game is Google-powered or not.
More details on Google Play Games are of course expected when the much awaited Google I/O kicks off on May 15th.