Apple has released the third beta of Mac OS X 10.6.7 for developers to thoroughly explore. No new issues have been included in this build (10J850) and developers are again asked to test graphics, AirPort, and Bonjour reliability.
The Mac App Store, introduced in the Mac OS X 10.6.6 update in early January, is also a major focus of the Mac OS X 10.6.7 update, which, given the lack of new issues in the latest build, should signal a public release in the next couple weeks.
Mac OS X 10.7 Lion is expected to be released this summer, taking cues from the successful evolution of iOS by bringing many updates to Apple's desktop OS, highlighted by features like Launchpad, full-screen apps, and Mission Control.
Stay tuned for release notes when Mac OS X 10.6.7 is available to the public, and don't forget to read up on best practices for upgrading your Mac.