Apple first began soliciting developers on Wednesday, inviting them to be among the first participate in the beta for OS X 10.8.2. Those who accepted the invitation began gaining access to the pre-release beta on Thursday.
The first build of OS X Mountain Lion 10.8.2 is known as Build 12C31a, those familiar with the software indicated. The combo update is available as a 642-megabyte download direct from Apple's developer website.
Apple has reportedly asked developers to focus their testing on Facebook integration with the beta build of OS X 10.8.2. System-wide Facebook integration is set to publicly launch with a software update to Mountain Lion later this year.
People familiar with the pre-release software also indicated that Apple has asked them to concentrate on Messages, Game Center, Safari and Reminders when testing OS X 10.8.2. The first beta is said to currently have no known issues.
Earlier Thursday, Apple publicly released OS X 10.8.1 for Mountain Lion, less than a month after the operating system update first went on sale via the Mac App Store. That software update provides fixes for iMessage, Migration Assistant, and audio when connected to Thunderbolt displays.