Speaking at the WWDC keynote in San Francisco tonight, Apple's Phil Schiller described Apple Mac OS X 10.7 Lion as 'a major release with over 250 new features' and '3,000 new APIs'. In a controversial move, Apple is making Lion available only through the Mac App Store, as a 4GB download from just £20.99. It will be available in July.

One of the new features is multitouch gestures. Commenting on the demonstration, Macworld's Jason Snell said: "The existence of the Magic Trackpad, plus its place a standard option on the iMac, shows just how much Apple believes multi-touch is a vital part of the future of the Mac."

Apple demonstrated scrolling, tap to zoom, pinch to zoom, and swiping on the desktop OS. The scroll bars disappear, magically appearing only when you scroll. The multitouch works from a touchpad or other pointing device, unlike interaction with an iPhone or iPad.

Apple also showed off another feature: full-screen apps. This built-in feature was described as important for small notebooks. You can keep an app running fullscreen, swipe to the desktop with multitouch gestures, and then go back.

The next feature Apple execs demoed was Mission Control. Akin to a combination of Exposé and Spaces, a simple gesture takes you to Mission Control, giving you a bird's-eye view of everything that's happening on your system.

On stage in San Francisco, Schiller and Craig Federighi demonstrated fullscreen apps, multitouch control and Mission Control, before Schiller introduced another, much-trailed feature: the Mac App Store. Apple claimed that the Mac App Store is now the number one channel for PC software sales. The Mac App Store is built right into Lion, and includes new features such as in-app purchase, push notifications, built-in sandboxing and faster updates.

Next up on the list of new features is Launchpad. Using Launchpad, a simple pinch gesture brings all of your apps on to the screen, like the iPhone Home screen). You can have multiple screens, and new apps bought from Mac App Store show up in your Launchpad. You can rearrange them or create folders.  

Apple also demonstrated three new features to make starting up and quitting work quicker: Resume, Versions and Auto Save. According to Apple, Resume takes you right back to where you were last time you used an app, or even undertook a system task. It remembers where everything is, and what you were doing. Similarly, Lion introduces Auto Save, a tool that means you no longer have to remember to save. You can Lock a file to prevent it from being auto-saved, but the name of your document is now a menu. Click on it and you can revert to last opened to get back to where you were.

Versions saves multiple past, well, versions of a document you are working on. You can share the current version, or go to the menu and click 'Browse All Versions', allowing you to go back to and work on an older version. You can have multiple versions open, and even copy and paste between them.

Schiller also introduced an easy way to move files between two computers: AirDrop. AirDrop is a peer-to-peer Wi-Fi-based network. You can look for other people in the vicinity using AirDrop, and simply drag and drop a file across. The other user then sees a request they can accept or dismiss. It's fully encrypted, and enabled right out of the box.

The final new OS X 10.7 feature Apple demostrated is a new interface for its Mail email app. According to Schiller, Mail is optimised for reading email, with a two column or three column view. It also works with fullscreen. You are prompted you for people and subjects, and even offered search suggestions. Like Gmail, Mail now has a conversation view, that shows you the entire thread that you can just scroll through, with attachments, and everything.

See also: Apple Mac reviews

See also: Apple Mac notebook reviews

Introducing the keynote, Steve Jobs said: "We're going to talk about three things today. If the hardware is the brain and the sinew of our products, the software is their soul."

Jobs described the Mac OS X is the heart of the Mac. It's 10 years old, and was built on UNIX, with ease of use and simplicity as its key selling points.

The WWDC keynote in San Francisco was attended by more than 5,200 attendees and, according to Apple, sold out within two hours.

Full coverage of the WWDC keynote

Macworld.com's Jason Snell and Dan Moren contributed to this story.