updated 04:53 pm EST, Tue December 18, 2012
Update includes no known issues
Apple is seeding a third beta build of OS X 10.8.3 to developers. The build is listed as 12D43, and includes no new feature additions, but also no known issues. Apple is asking developers to concentrate on testing AirPlay, AirPort, Game Center, Safari, and graphics drivers.
The previous build was released on December 5th. Given that Apple often puts out several betas of an OS X update before making it public, it may be that v10.8.3 will only go wide sometime in January.