Mac OS X 10.8.4:
- Login: Honor the “Reopen windows when logging back in” setting when set to off, instead of insisting on launching all my apps again. Every. Single. Time.
 - Messages: Stability and performance improvements that prevent it from crashing every single day upon startup or searching.
 - Messages: Fix for 
imagentrandomly losing messages. - Safari: Corrections to history menus in order to display real URLs from pages reached via Google search results instead of useless 
www.google.comredirect URLs. - Safari: Top Sites now cache site snapshots instead of re-creating them every time, trying to log in to sites for you and wasting CPU.
 - Messages: Added official support for Facebook Chat and IRC.
 - Mail: Added support for custom header fields to smart folders.
 - Mail: Improved Exchange meeting request handling so that it actually works.
 - Calendar: Fix Exchange support to match recent iOS bug fixes, so that refusing a meeting invitation doesn’t result in automatic cancellations being sent to all attendees.
 - Calendar: Fixes to Exchange meeting request handling to avoid munging participants and timezones.
 - Terminal: Added support for mouse events and corresponding escape sequences, like mouseterm and iTerm.
 - Python: Upgraded to 3.3 and 2.7.4, with updated ScriptingBridge bindings.
 - Share: Third-party support API.
 - Share: Added Google+, Pinterest and Flickr.
 - Share: You can now paste images onto the share panel from the clipboard.
 - Twitter: Added option to set handler application when clicking on notifications instead of forcing me to use their website.
 - Notification Center: Added support for image thumbnails.
 - Reminders: Streamlined UI.
 
iOS 6.2
- System: New Apple Visual Guidelines.
 - Lock Screen: Slide gestures to reveal Dashboard.
 - Dashboard: Support for sandboxed HTML5 widgets.
 - Springboard: Allow for arbitrary placement of icons and Dashboard widgets in grid positions.
 - Accessibility: Support for 
Cmd-Tabtask switching when using a Bluetooth keyboard. - Keyboard: Swiftkey mode.
 - Mail: Smart folder support.
 - Messages: Added XMPP support for third-party service providers including Google and Facebook.
 - Safari: Improved UI for searching in page.
 - Safari: Reinstated simple JavaScript console.
 - Share: Improved third-party API.
 - Share: Added Google+, Pinterest and Flickr.
 - Siri: Added support for Portuguese, despite only being spoken by 215 million people on Earth.
 - Notification Center: Added support for image thumbnails (modelled on MMS).
 - Notification Center: Added shortcuts for volume and brightness.
 - Notification Center: Fixed blank screen hang when starting to post to Twitter or Facebook.
 - iCloud: Improved Reading List and iCloud Tabs so that they actually sync with desktop within an hour.
 - iCloud: Fixed Core Data syncing.