Apple on Thursday released a developer preview of Mac OS X Lion, the next incarnation of the Mac operating system. The new version sports a number of features that weren’t showcased when Apple offered a sneak preview of Lion back in October.

Leading the new feature charge is AirDrop, which sounds like a Dropbox alternative. In press materials announcing the developer release, Apple describes AirDrop as “a remarkably simple way to copy files wirelessly from one Mac to another with no setup.”

Another new feature called Versions promises to automatically save successive versions of a document as that document is created, which Apple says will make it easier to revert to previous versions of a file. That feature seemingly dovetails nicely with AutoSave, which automatically saves documents as you work.

Also new is Resume, which recreates the last state of your apps when you relaunch them or restart your Mac, much like multitasking apps do under iOS 4.0.

The iOS similarity is no accident. Apple has touted Lion as an operating system that takes the best features of its mobile OS and delivers them to the desktop. Lion offers full-screen support for applications and support for multitouch gestures. Other previously announced features include Mission Control, which provides a view of open full-screen apps and the Springboard-esque Launchpad.

Registered Mac Developer Program members can get Lion directly from the Mac App Store. The final version of Lion will be available to everyone this summer, according to Apple.

“The iPad has inspired a new generation of innovative features in Lion," said Phil Schiller, Apple’s senior vice president of worldwide product marketing in a statement announcing the developer release. “Developers are going to love Mission Control and Launchpad, and can now start adding great new Lion features like full screen, gestures, Versions and Auto Save to their own apps.”