Today, Apple has begun notifying participants in its early software seeding program (AppleSeed) that OS X Mountain Lion 10.8.2 is on the way. According to the email notification, the 10.8.2 seeding will begin soon. AppleSeed and Mac Developer builds typically coincide in release timing, so it appears that registered Mac developers will, too, receive the first 10.8.2 build very soon.
You are invited to participate in the next Mountain Lion Software Update seed project, 10.8.2. Apple will provide you with the pre-release software. Once builds are available, we ask that you install and test each build to help us make sure that this is a high quality release!
With OS X Mountain Lion 10.8.1 coming soon as a maintenance release, this new 10.8.2 install will likely be an iOS 6 compatibility release. iOS 6 includes a number of features that will require a Mac update. These features include Apple ID phone number merging for iMessage and FaceTime, Facebook integration, Shared Photo Streams, and other iCloud enhancements.