Steve Jobs and company showed off the latest innovations coming to Mac OS X 10.7 “Lion” on Tuesday at Apple’s Worldwide Developer Conference (WWDC), which kicked off in San Francisco. Apple revealed that Lion will be released in July for $29.99, and will be available exclusively through the Mac App Store in a 4GB download, suitable for installing on all authorized Macs.

[ad#Google Adsense 300×250 in story]Lion sports more than 250 new features. Some of the features were first revealed at a special “Back to the Mac” event last October, but Apple VPs Phil Schiller and Craig Federighi fleshed those features out, and others, in more detail.

Lion incorporates systemwide support for full screen applications, along with new multi-touch gesture support similar to how iOS works, with rubber band-style scrolling, page and image zoom and full-screen swiping.

Mission Control offers what Apple calls a “bird’s-eye view” of everything that’s happening on your Mac, with Exposé, apps, Dashboard and Spaces all combined into a single interface. Launchpad is a new interface element that makes it possible to launch application from a single full-screen layout; you can organize apps into folders and pages, similarly to how they’re laid out in iOS.

Lion also features a redesigned Mail app with widescreen layout; it adds a new “Conversations” function that groups related messages. Mail in Lion also has a new search feature that can suggest matches by person, subject and label as you type. It includes built-in support for Microsoft Exchange 2010.

Apple also revealed that Lion Server will be available as a separate download for users who have already installed Lion. It will cost another $49.99.

Apple says that Lion requires a Mac with a Core 2 Duo, i3, i5, i7 or Xeon processor and 2GB RAM. This appears to exclude early Intel iMacs which had Intel Core Duo processors only.