As noted by 9to5Mac, Apple today seeded build 12E52 of OS X 10.8.4 to developers. The release comes seven days after the previous build 12E47 and marks the seventh beta iteration of OS X 10.8.4.
The update is available through the software update tool in the Mac App Store and Apple's Developer Page.
Article Link: OS X 10.8.4 Build 12E52 Seeded to Developers