People familiar with the matter say the 38.5MB beta release was accompanied with a set of release notes identifying no known issues.
Instead, the Mac maker asked developers to focus their testing efforts around USB, PAC proxies in Safari, Active Directory and Microsoft Exchange support in Mail.
Apple also made a specific request for testers to evaluate WiFi and audio when connected to a Thunderbolt display, suggesting it has attempted to address problems in this area after MacBook Air users said they were experiencing audio issues -- static, distortion and crackling -- when they connect their notebooks to the company's latest 27-inch LED display.
Apple has historically aimed to push out its first maintenance release for major operating systems milestones in a swift manner, suggesting we could see a formal release of the software in the coming weeks.
Mac OS X 10.8 Mountain Lion made its debut on the Mac App Store on July 25th. It saw a record 3 million downloads in just 4 days, immediately making it Apple's most successful release for the Mac ever.
For its part, Mac OS X 10.8.1 surfaced in the news just hours ago when it was listed as part of a system profile for an unreleased 13-inch MacBook Pro with Retina display that was apparently used to submit benchmark scores to Geekbench. That prototype MacBook Pro was running build 12A2066 of the forthcoming update while the build released to developers friday carried build number 12B13.