Apple has just rolled out its first OS X 10.9.2 beta to registered Mac developers following the OS X 10.9.1 public release via App Store just a few days ago. The new bug-fix and maintenance update is now available for download via Mac App Store as well as Mac section of Apple's online developer portal.
According to 9To5 Mac, the key areas of developer focus as revealed in the changelog include Mail, Messages, Graphics Drivers and VoiceOver. Significant feature changes ported into the OS X 10.9.2 Beta are as follows: deeper integration of FaceTime Audio into Messages and FaceTime apps, besides minor tweaks to Mail app.
The new beta update for OS X Mavericks also brings bug-fixes and performance improvements as part of Apple's periodic maintenance update. You can manually download the latest OS X Mavericks 10.9.2 Beta via Mac App Store by tapping the update button.
As this is a pre-release build, Apple warns new developers in its release notes that they should not install the software on a production unit with important data, as it could harbour critical bugs that affect the performance of the system.