At a Media Event on Tuesday, Apple released OS X Mavericks and will be available to download on the Mac App store for FREE to all users today. Apple previewed Mavericks at WWDC in June.
Mavericks will include enhanced multiple-monitor support, big improvements to the Notification Center, an improved Finder, better power management, and improved performance in Safari.
Mavericks also includes a number of brand new features, including a new iCloud Keychain function to save passwords across iOS and Mac devices, new Mac apps for iBooks and Apple Maps, along with UI redesigns for a number of built-in applications.