Apple today seeded build 12D58 of OS X Mountain Lion 10.8.3 to developers, marking the seventh beta iteration of the newest version of Mountain Lion. 10.8.3 was first seeded to developers in November.
Build 12D58 comes a week after build 12D54, and like the previous build, contains no known issues or features. Build 12D54 brought significant changes to WiFi, and asked developers to focus on testing AirPlay, AirPort, Game Center, Graphics Drivers, and Safari.
This post originally referred to Build 12D58 as the eighth developer seed of OS X 10.8.3 when it was actually the seventh seed.