Preview at WWDC likely in June, followed by September launch.
OS X 10.8.1 May Address Mountain Lion Battery Life Issues
Softpedia now reports that it has heard from one developer claiming that OS X 10.8.1, which entered developer testing just days after Ars Technica's report, does indeed address this battery life issue.
“Until I installed 10.8.1, my MacBook was showing 4h:05m after a full charge,” he said, referring to the amount of time before the battery would deplete completely.Another report from Apple's discussion forums describes a similar major boost to battery life under OS X 10.8.1, but results from our own forums are less clear. Several users have reported no changes to their battery life while others suggest that there has been some improvement, but it appears that specific testing by those who were affected by the Mountain Lion battery life drop has not been well-documented.
“After installing 10.8.1 it's showing over 8h,” he said. “I'm now able to use my Mac throughout the day again without having to carry my charger,” said the happy developer.
OS X 10.8.1 will be the first maintenance release for OS X Mountain Lion, and such updates are generally pushed quickly through the development and testing processes in order to address the most severe bugs cropping up with the initial public releases of new operating systems. Significant battery life issues would seem to qualify as something Apple would want to address in this update, but the company has not specifically addressed the topic in release notes or other documentation associated with the test builds being distributed.