Apple today announced that Mac OS X version 10.7 Lion will be available in July as a download from the Mac App Store for $30.00 (only as an upgrade to Mac OS X version 10.6 Snow Leopard). The eighth major release will add more than 250 features and 3,000 developer APIs to the company's desktop operating system. Mac OS X Lion Server will require Lion and will also be available next month from the Mac App Store for $50.00.

As expected, the OS will not be available for purchase in retail stores on a physical optical disc. The download will weigh in at around 4GB, or around the size of a typical DVD.

Lion adds new multitouch gestures and animations that let you interact directly with content on the screen. New gestures include momentum scrolling, tapping or pinching your fingers to zoom in on a web page or image, and swiping left or right to turn a page or switch between full screen apps (read a full preview of OS X Lion here).

The addition of system-wide support for full screen apps means developers can take advantage of the entire display. With a single click, your app fills the display and you can swipe from one window to another, between full screen apps, or back to your Desktop, Dashboard, or Spaces without ever leaving full screen. Apple has updated its iWork and iLife apps, as well as Safari, iTunes, Mail, FaceTime, and others, to take advantage of full screen apps.

Apple has also added Mission Control, which combines Exposé, full screen apps, Dashboard, and Spaces into one unified experience for a bird's eye view of every app and window running on your Mac. With a simple swipe, your desktop zooms out to display your open windows grouped by app, thumbnails of your full screen apps and your Dashboard, and allows you to instantly navigate anywhere with a tap.

With Lion, the Mac App Store is now built-in, so you can buy apps with your iTunes account, download, and install them. Apps automatically install directly to Launchpad (a new home for all your apps), and with Lion's release, the Mac App Store will be able to deliver smaller "delta" app updates and new apps that can take advantage of features like In-App Purchase and Push Notifications.

Lion includes a redesigned Mail app with a new widescreen layout and built-in support for Microsoft Exchange 2010. The new Conversations feature groups related messages into a scrollable timeline while the improved search feature suggests matches by person, subject, and label as you type.

"The Mac has outpaced the PC industry every quarter for five years running and with OS X Lion we plan to keep extending our lead," Philip Schiller, Apple's senior vice president of Worldwide Product Marketing, said in a statement. "The best version of OS X yet, Lion is packed with innovative features such as new Multi-Touch gestures, system-wide support for full screen apps, and Mission Control for instantly accessing everything running on your Mac."