Yesterday evening, Apple seeded members of their AppleSeed program, as well as registered Mac developers, with a new pre-release build of OS X 10.8.3. Apple has also changed the way they distribute updates, and is now pushing updates for pre-release versions of OS X directly through Software Update (via the Mac App Store).
In order to take advantage of updates through Software Update, developers must first install a tool to configure the new update method. Apple has also implemented a system to alert the tester any time a new update is available, prompting them to install it.
As with previous builds, developers are asled to focus on AirPlay, AirPort, Graphics and Game Center, and has added Safari as an additional focus point. The update is available now to registered developers through Apple’s Mac Developer Center. The first beta of 10.8.3 was seeded to developers on November 26.