Apple today issued build 12E33a of OS X Mountain Lion to developers, eight days after build 12E30 was released. Build 12E33a marks the third beta iteration of OS X 10.8.4.
The update is available through the software update tool in the Mac App Store and it should appear on Apple's Developer Page shortly.
Article Link: Apple Seeds Build 12E33a of OS X Beta 10.8.4 to Developers