Apple on Tuesday seeded build 12D50 of OS X 10.8.3 pre-release to developers with no known issues.
From Apple Insider:
The new build comes a little over two weeks after Apple seeded the previous 12D44 build, which itself arrived with no known issues and minor under the hood changes to the upcoming version of Apple's operating system.OS X 10.8.3 Mountain Lion beta seeded to developers with minor changes
People familiar with the release told AppleInsider that Tuesday's build notes are identical to the previous two seeds that came out in December, with developer focus areas including AirPlay, AirPort, Game Center, Graphics Drivers and Safari.