Next version of iOS with overhauled notifications, lock screen, Messages, Apple Music, and much more.
Apple Seeds New 13A598 Build of Mavericks to AppleSeed Members
Separately, 9to5Mac reports that this build may be a GM candidate, according to AppleSeed members, while other sources have said the final release build will be several versions newer. The OS was reportedly nearly ready for release a few weeks ago, but was pushed back because of "critical bugs".
Since being announced at WWDC, OS X Mavericks is said to have picked up a few minor unannounced features. Namely, the Messages and FaceTime applications have received the ability to block phone numbers and Apple IDs from sending the Mavericks user messages and/or FaceTime calls. This addition brings parity to iOS 7 and the two operating systems will sync in this manner.OS X Mavericks, which is expected to be released this fall, includes multiple new features like a tabbed Finder, full screen dual monitor capabilities, Safari improvements, and a new Maps app.
Apple is reportedly targeting a late October launch for OS X Mavericks.