Apple is closing in on finishing up work on OS X Mavericks ahead of its public launch, according to a source familiar with the new operating system’s development. This source says that the operating system will reach Golden Master status internally by the end of this week or early next week, and it will be labeled as a build number in the high 13A590s or low 13A600s. This will be a slight increase over the current developer build that is version 13A584. Earlier today, Apple seeded OS X Mavericks build 13A598 to members of its AppleSeed program, but it is unclear if that new version will ever reach developers.

AppleSeed members believe that this build is a GM candidate, but a source says that Apple is already internally seeding newer builds. The source has also corroborated our previous report by indicating that OS X Mavericks is currently scheduled to arrive on the Mac App Store within the last ten days of the month of October. Mavericks was supposed to reach GM status a few weeks ago, but critical bugs have kept pushing back the release, according to claims from sources.

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. While this enhancement is probably not surprising, it has not been present in any Mavericks Developer Preview to date. (Update: The aforementioned addition is coming in a point update in the coming weeks) Mavericks will also bring the launch of iCloud Keychain…

With OS X Mavericks nearing its public debut, and iOS 7 having arrived last month, Apple is said to already have diverted the majority of its OS X and iOS resources to development of the next two Apple operating systems: OS X 10.10 and iOS 8.

Views to 9to5Mac from 10.10 began in September

OS X 10.10 is internally codenamed Syrah (yes, another wine), and sources hint that Apple has been toying with a new design across the system that is akin, but not as dramatically different, to the new designs found in iOS 7 and iCloud.com. As for iOS 8, development of that OS is making headway, and it will likely bring feature enhancements to Maps.

Yesterday we reported that Apple has begun training its AppleCare support staff on OS X Mavericks. While OS X 10.10 and iOS 8 are not scheduled to be announced until next summer, users can expect a few updates in the near future (in addition to Mavericks): a new version of OS X 10.8.5 launched today, and we expect iOS 7.0.3 and iOS 7.1 to arrive by the end of the year. Apple also has several hardware releases still up its sleeve for this fall including multiple new iPads, Macs, and perhaps a fresh TV-related device.

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