According to various sources around the internet, like 9To5Mac Apple has begun seeding OS X 10.8.1 Build 12B19 through the Mac App Store. I checked this morning to see if the update was available for my MacBook Air, but it did not pick anything up; I reside in Canada. The update is rolling out around the world as I type, and thus should be available for all shortly.

Download OS X 10.8.1 Build 12B19

It looks like this update mainly focuses on resolving a handful of persistent bugs users have been experiencing since the launch of Mountain Lion, and there was no mention of improved battery life for Mac laptops like previously rumoured. You can take a look at the changelog for OS X 10.8.1 Build 12B19 below:

  • Resolve an issue that may cause Migration Assistant to unexpectedly quit
  • Improve compatibility when connecting to a Microsoft Exchange server in Mail
  • Address an issue playing audio through a Thunderbolt display
  • Resolve an issue that could prevent iMessages from being sent
  • Address an issue that could cause the system to become unresponsive when using Pinyin input
  • Resolve an issue when connecting to SMB servers with long names
  • Address a issue that may prevent Safari from launching when using a Proxy Automatic Configuration (PAC) file
  • Improve 802.1X authentication with Active Directory credentials

Depending on the model of your Mac computer that you are updating, OS X 10.8.1 has been said to be anywhere between 7-30MB in size. We will keep you updated if more develops off this Mountain Lion update, but until that time stay tuned and let us know if this update has had any significant impact on your performance or battery life in the comments section.