People familiar with the matter say the first external build of the software -- labeled Mac OS X 10.6.3 build 10D522 and weighing in at 665.7MB in barebones delta form -- includes a total of 221 code corrections to 92 distinct system components.
Among those components receiving the most attention are AppKit, CoreMedia, Desktop Services, FileSync, Fonts, HIToolbox, iCal, Mail, MobileMe, and QuickTime Player X, those same people say.
Other individual and welcomed enhancements include improvements to Snow Leopard's automatic spell correction, and fixes for crashes while printing and using AppKit, the Dock, iCal, Mail, Photo Booth, Rosetta, Spotlight, Screen Sharing, and Software Updater.
In total, nearly 60 individual pieces of crash-prone code have reportedly been addressed as of build 10D522.
Apple also reportedly noted four known issues with Wednesday's beta, including hangs in iTunes, and potential anomalies while updating applications, viewing Display preferences, and navigating the ColorSync Utility Filters tab.
Nearly a month ago, Apple began preparing the first beta of 10.6.3. However the Mac maker apparently chose to withhold the Snow Leopard update from broader distribution until after the holidays, during which time it compiled and evaluated roughly 15 more builds.
The last maintenance update for Snow Leopard, Mac OS X 10.6.2, was released in November. It addressed a publicized bug that could delete a user's account data when logging in and out of a guest account. The update also included native support for the multi-touch Magic Mouse.
Two months before that, in September, Apple released Mac OS X 10.6.1. That update came less than two weeks after the late August debut of Mac OS X 10.6 Snow Leopard. It addressed a number of stability, compatibility and security issues for the Mac.