Apple today seeded build 12D50 of OS X 10.8.3 Mountain Lion to developers, the fifth beta release reports 9to5Mac. The first 10.8.3 beta was seeded back in November, and the third and fourth releases were released in December.
Though the update comes with no known issues or new features, as before Apple has asked developers to focus on AirPlay, AirPort, Game Center, Graphics Drivers, and Safari in their testing. Registered developers can download it via the Apple Developer Page.
Originally posted here:
Apple Seeds Build 12D50 of OS X Beta 10.8.3 to Developers [Mac Blog]