Apple is planning to release a new build of OS X 10.8.3 Mountain Lion this year. The firm release date for OS X 10.8.3 hasn’t surfaced the Internet yet, but the first Beta Testing date for this new build of OS X 10.8.3 with unknown changes has surfaced the Internet. In the preceding month of October, Apple informed the external OS X testers group called AppleSeed about the upcoming OS X 10.8.3 build testing release to be done soon. Later today, Apple informed the same AppleSeed group about the previous message that it was sent to them early.

As noted by 9to5mac, the message sent by Apple to AppleSeed group for OS X 10.8.3 states:

The invites were sent out a little too early. We are working hard to provide you with a seed build soon, but we wanted to let you know that you have not missed any seed announcements.  Please enjoy the USA Thanksgiving holiday!  The seed team will be enjoying a break as well.  Look for more information about the 10.8.3 seed during the week of November 26th!

In the letter above, Apple stated that the first Beta Version of OS X 10.8.3 would be released after thanks giving holidays, noticeably around November 26. Therefore, we can expect a beta of OS X 10.8.3 on November 26 or some where around this date. As usual, we don’t know about the changes that Apple is going to make in this new beta of OS X 10.8.3. We are very dependent on the AppleSeed Team. The ball is now in their court. It is up to them to reveal the change log or keep the change log secret.

We expect the change log to be unveiled as soon as AppleSeed group gets hands on this new build because when it comes to Apple, to leak the information about an upcoming product is the first priority of every one. To leak the information at first helps them to regain some PR in the world of rumors.