Apple on Thursday offered a new beta release of OS X Mavericks 10.9.2. The new build, identified as build 13C39, is now available for download from the Mac Dev Center. It's available for registered Mac developers only.
Changes made to the update are covered by Apple's non disclosure agreement, so we'll refrain from posting details on what's changed. We'll definitely post details when it's finally out in the world and ready for general consumption, though, so please stay tuned.