Lion is a significant release when compared to prior generations of the Mac OS X operating system.  Apple has gone against the grain of how users have traditionally interacted with the OS X operating system.  Several new features (over 250) will change how users work with a Mac including:

• Multi-Touch gestures - change the way users interact with a Mac.  The operating system is more intuitive than ever.  Key new gestures include rubber-band scrolling, page and image zoom, and full-screen swiping.
• Mission Control - is an encapsulation and rebirth of prior OS X features Dashboard, Exposé, and Spaces.  In conduction with full-screen apps users gets a great way to see everything running on a Mac.  Via a trackpad swipe, the Mac OS X brings up Mission Control where you can view just about everything on your Mac and switch to it with a click.
• Full-Screen Apps - Lion takes the Mac OS X app experience to the next level via full-screen systemwide support that takes advantage of your entire screen space.  You're able to run multiple full-screen apps at a given time alongside standard apps.  Think of it as a way of fully leveraging the power of Mac OS X Lion and your screen.
• Launchpad - Launchpad is a new, full-screen view of the apps installed on your Mac.  From the standard built-in apps and utilities that come with Mac OS X to the apps you installed via the Mac App Store and third-party installed, you can easily launch and find your apps. After you click the Launchpad icon in the Mac OS X Dock, the one windows on your Mac fade away and get replaced by a full-screen app view.  You can arrange your apps as you do on your iPhone, iPad, and iPod touch - you place them in the order of your choosing or you can group and organize them into folders.  Deleting an app from your Mac is easier than ever.
• Resume - makes working with your apps that much easier and streamlined.  Return to your apps after in the state they were in when they were closed.  Software updates are now a breeze as you do not need to save your work, close an app, and set it up again following an update.
• Auto Save - The manual save process is shown the door in Lion.  You concentrate on your work while Mac OS X Lion automatically saves what you're working on.  You'll be more productive!
• Versions - Versions is a cool new timeline-browsable snapshot feature that keeps a historical track your documents.  This is another productivity booster allowing you to review your past work, restore an old version of your work, or copy and paste from an old version to a new one.
• AirDrop - makes wirelessly sharing files with people nearby a breeze, you don't even need Wi-Fi or set anything up.  All you do is click the AirDrop icon in the Finder sidebar and your Mac auto detects other AirDrop users in your vicinity (30 feet range). Sharing a file is easy, all you do is drag the file that person's name and once they accept, the file is sent to them with encryption protection and shows up in the Downloads.  Say goodbye to USB thumb drives.

Mail and the Mac App Store
Lion also brings forth a major rework to Mail.  From widescreen view to the new favorites bar, to conversations and timelines, Mail is easier to use and helps you stay organized.

Lion also includes the Mac App Store, a feature that Apple implemented in the Mac OS X Snow Leopard 10.6.6 update.  The Mac App Store is a great way to find, purchase, and download apps for your Mac.  Choose from a variety of free and paid apps.

For an overview and history of Mac OS X, please read What is Mac OS X?

Upgrading to Mac OS X Lion
Lion will only run on Intel-based Macintosh computers specifically those equipped with an Intel Core 2 Duo, Core i3, Core i5, Core i7, or Xeon processor.  Lion will be released via the Mac App Store for $29.99 in July 2011.  Lion will be the first version of Mac OS X that is not available on disc.

Users need to be running the latest version of Mac OS X Snow Leopard before the can upgrade to Lion.  The server version of Lion will be priced at $49.99 for current Mac OS X Snow Leopard Server users.