People familiar with the software indicated to AppleInsider that select members of Apple's developer community were provided with invitations on Wednesday. Such invitations are sent out ahead of the introduction of a new beta.
No details on exactly what OS X 10.8.3 will include are available. The pre-release beta period allows developers to test their applications and find potential bugs before the update is released to the public.
The last update to Mountain Lion, OS X 10.8.2, was issued in mid-September. It was a major update that added system-wide integration with the social networking site Facebook.
Mountain Lion debuted in July on the Mac App Store as a $20 upgrade. It also comes preinstalled on all new Macs.