We've got a good one for you today. A teardown of MyGlass, yes that's right, the Google Glass companion app, has given us what looks like the entire Google Games Service feature list. You just can't make this stuff up.
The games service probably has nothing to do with Google Glass; Glass can't run complex apps. The Glass team accidentally shipped the full suite of Google Play Services with their new app, which is not normal. This included a never-before-seen backend for an extensive multiplayer gaming service, with just about every gaming feature you could possibly imagine.
To understand just what has happened, and why this is not related to Glass at all, we've got to talk about "GMS." GMS originally stood for "Google Mobile Services"; they changed the name to "Google Play Services," but never changed the acronym.