Coming just a few weeks after the public release of 10.8.3, Apple has seeded the latest beta build to developers today. Mountain Lion 10.8.4 is available only to those belonging to the Apple Developer network and the build version is 12E27.
Mountain Lion 10.8.4 came with the standard issue of release notes according to our insider but those notes did not contain anything specific as to what was addressed or updated in this release. The only things mentioned in the focus areas of the notes were WiFi, Safari and Graphics.
As expected, there is no indicated date of when Mountain Lion 10.8.4 will be available to the public. In the case of 10.8.3, there were over a dozen revisions to the build over the course of 5 months developers had access to it. That was a long beta cycle even by Apple standards so it is difficult to say if that will be the case again on this release.
It is also worth noting that February marked the one year anniversary of Mountain Lion being announced. 10.8.4 could very well represent one of the last major builds of Mountain Lion as anticipation of a new OS X, 10.9, is expected soon. How soon and if this is indeed one of the last updates for 10.8, only time will tell.
Mountain Lion 10.8.4 is available through the Apple Developer network which is $100 per year to join. More information can be found on the Developer site.