Today, Apple has seeded the first beta build of OS X Mountain Lion 10.8.1 to developers. The build number is 12B13 and it is available from the Mac Developer Center web portal. Apple says that the initial 10.8.1 seed has zero known issues. However, Apple asks developers to focus on testing Active Directory, Microsoft Exchange in Mail, PAC Proxies in Safari, SMB, USB, and WiFi and Audio when connected to the Apple Thunderbolt Display.

Earlier this week, Apple informed participants of the AppleSeed program that they would receive the initial Mountain Lion 10.8.1 build soon.

The DMG to perform a delta update from OS X Mountain Lion 10.8.0 is only 38.54MB. The installation itself takes up 36.4MB of space on a Mountain Lion Mac.

According to a reader who installed OS X 10.8.1, Facebook integration is yet to be included. Perhaps Facebook will come as a separate download,like it currently does for developers, or perhaps it will come in a later beta or another version of OS X Mountain Lion altogether. Also, for those wondering, it does not seem like this release has iMessage phone number merging.

Gallery of installation:

We’ve put the full release notes after the break:

OS X Mountain Lion 10.8.1 build 12B13 Seed Note

OS X Mountain Lion Update 10.8.1 is an update to OS X Mountain Lion 10.8.

Installation Instructions

The OS X Mountain Lion 10.8.1 Update (Delta) updates OS X Mountain Lion 10.8 GM.

Please be aware that you will not be able to revert back to your previous system after updating. Please install this update on a system you are prepared to erase if necessary.

Known Issues

– None

Focus Areas

– Active Directory

– Microsoft Exchange in Mail

– PAC proxies in Safari



– Wi-Fi and audio when connected to Thunderbolt display

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