New in 10.8.2 is support for Facebook, matching the similar feature launched in iOS 6. Desktop apps that need your Facebook credentials will now be able to access them from your settings in System Preferences, notifications from Facebook will appear in Notification Center, and your Facebook friends’ contact information will appear in the Contacts app.
Game Center scores some updates, as well. You can share your high scores to Facebook, or via Twitter, Mail, or Messages, and you can also challenge your Facebook friends to beat your score from within the app.
And, at long last, iMessages sent to your iPhone number should appear in the Messages app on your Mac. FaceTime calls to your phone number should ring on your Mac, as well.
Other new features include Power Nap support for the MacBook Air (Late 2010), support for sending passes to Passbook on iOS 6, the ability to share Reminders lists, and new sorting options for Notes.
Save As devotees, take note: 10.8.2 adds an option to discard the changes in the original document when you use the recently-restored Save As option. That addition restores the original Save As behavior to which Mac users were long accustomed before the feature first vanished in Lion, and reappeared with different functionality in the original Mountain Lion release.
Twitter notifications are handled better in Notification Center. And Google searches from the location bar now support SSL as well.
Finally, 10.8.2 also includes Safari 6.0.1, a minor update to Safari that addresses several security issues.
Mac OS X 10.8.2 is available as a Mac App Store update, as well as via Apple’s Downloads pages; you can download the delta or combo updater. (The delta updater includes only chances since OS X 10.8.1; the combo updater includes all changes since 10.8.0.)
Updated 9/19/12, 4:35pm, to add links to downloadable updaters and to add mention of Safari 6.0.1.