Apple is seeding another beta of OS X 10.8.3 to developers. The build is listed as 12D78, and appears to have no known issues. As with past builds
, Apple is asking developers to focus testing on AirPlay, AirPort, Game Center, graphics drivers, and Safari.
Even though v10.8.3 is just intended for maintenance, the release has seen some of the longest development of any OS X update. It's now in its thirteenth seed, whereas most OS X updates go through less than 10 before reaching the public. It's possible, though, that v10.8.3 will be the last major Mountain Lion update before the OS' successor is announced.