On Tuesday Apple officially seeded the fourth beta of the next-generation Mac OS, code named Sonata. As mentioned long ago, and recently announced by Steve Jobs at Macworld, the release has now been renamed Mac OS 9.0. The system update was previously deemed Mac OS 8.7.
As with each build of the Mac OS that Apple seeds, they are each assigned their own individual code name for reference purposes. Beta 3 was code named \"Signed\" and hence beta 4 is code named \"Sealed.\" However, since Apple has a tradition of naming the builds with an \"S\" word to temporarily rename the \"Special\" menu, it is unlikely that beta 5 will be code named \"Delivered.\"
Regardless, Apple has informed developers that Sonata development is winding down, and of course the feature set has been frozen at this point in time. The final few builds will focus on clearing out all of the known bugs, allowing the system to move onto the final candidate stage.
Sonata has not been know to be incredibly stable, even in the beta stage. This may be due, partly, to fact that the release packs over 50 new major features and little to no improvements to the systems under-workings. With that said, sources are noting serious instability issues on certain Yosemite Power Macintosh G3 units.
Apple still a lot of time to hammer out these issues and make sure the update passes all of their quality assurance tests, as Mac OS 9.0 is not expected turn Golden Master until late August or early September. The release will cost customers $99 and will hit retail stores and mail order catalogs sometime in October.