Apple's description of Safari 6.0.2 is particularly terse: "Safari 6.0.2 is recommended for all users running OS X Mountain Lion v10.8.2 and includes security updates."
The Safari update was also released for OS X Lion v10.7.5, the main difference being that the Lion update is delivered via Software Update (as of this writing the installer has yet to be made available via Apple's Support Downloads page) while Mountain Lion users install it via the Mac App Store.
When iTWire tried to download the Mountain Lion update, we initially encountered the "NSURLErrorDomain error -3001" being reported by multiple users. When we checked again before publishing this article, the update had disappeared from the Mac App Store.
Both issues were in WebKit, the framework used by Safari and other HTML-based applications.