Apple's new Mr.Personality, Craig Federighi, took to the stage at the Yerba Buena Arts Center toward the beginning of an iPad-focused media event today to re-introduce OS X Mavericks.

The news wasn't in the updated Mac operating system itself, which we first saw back at Apple's Worldwide Developers Conference over the summer – rather it was in the price of the upgrade, which is available for free starting today.

According to Federighi, the process of getting OS X Mavericks on to your Mac will be as simple as downloading an app from the Mac App Store, and will be a single-step upgrade process, even for people using hardware as old as a 2007 iMac who haven't updated since OS X Snow Leopard.

Apple is clearly trying to unify the Macintosh experience, even for those that are particularly slow to upgrade. In the past, upgrades have cost users $20 or more.

We were already introduced to the new features of OS X Mavericks at WWDC, but just to recap, the upgrade will increase performance, according to Federighi. On stage at the event, he claimed that a compressed memory feature would allow 6 GB of data to fit in just 4 GB of system RAM. Additionally, efficiency improvements would add up to an hour and a half of battery life per charge to certain Macs, just by upgrading.

Also new to the Mac in Mavericks are iBooks, notifications, Maps and tagging ability. Improvements to the calendar app, Safari, multiple display capability and iCloud keychain help round out the package.