Following its notification of the upcoming release, Apple has seeded the first build of OS X Mountain Lion 10.8.2 to developers. It is build number 12C31a, and Apple says to focus on Facebook, Messages, Game Center, and Reminders.
OS X Mountain Lion 10.8.2 build 12C31a Seed Note
OS X Mountain Lion Update 10.8.2 is an update to OS X Mountain Lion 10.8.
The OS X Mountain Lion 10.8.2 Update (Combo) updates OS X Mountain Lion 10.8 build 12A269 GM or 10.8.1 build 12B17 or later build.
Please be aware that you will not be able to revert back to your previous system after updating. Please install this update on a system you are prepared to erase if necessary.
– Game Center
Earlier today, Apple released the first maintenance update of OS X Mountain Lion (10.8.1) publicly.