The Mac OS X 10.7 Lion developer preview was released along with new MacBook Pros on Thursday. I had the chance to download Mac OS X 10.7 and play around with some of the new features that Lion brings to the table. Apple said in their Lion press conference that 10.7 Lion brings some iOS style improvements to core parts of the OS, and it’s very clear from this preview that Apple is going all-in with touch-based controls. Apple’s new desktop OS and existing mobile OS feel very similar.

Here are some of the most notable changes and useful new features that I’ve found so far.

Improved gesture support

To take full advantage of 10.7 Lion’s new features, you need to be using a trackpad. Whether it’s a MacBook trackpad or a Magic Trackpad, Apple has focused on seriously improving the control of the OS through the pad. Two-finger scrolling now follows their touch interfaces in direction by default (move fingers up to go down, and down to go up), but you can switch it back if you’d rather have it the way it was in 10.6 and below.

With three finger gestures, the default behavior now is to switch between Spaces. You can literally fling the spaces around as if they are all lined up in a row (a la iPhone home screens), and the new Dashboard space is lined up to the left of everything. Dashboard no longer appears as an overlay on the desktop, but is rather given its own Space, and the new “Mission Control” feature can be accessed in the space “above” all of the other spaces.

Flinging around in between Spaces and to Mission Control with finger gestures feels like computing in the future, like I’m manipulating those giant screens in Minority Report and throwing information around with my hands. It’s definitely a happy medium between a desktop OS and touchscreen-style controls.

“Mission Control” and Launchpad

Apple has introduced two major new UI enhancements in 10.7 Lion, “Mission Control” and Launchpad. Mission Control takes spaces and expose and merges them, giving you access to every application window and Space you have set up in one convenient screen. Launchpad brings the iOS Springboard to Mac OS X, allowing you one-button access to every app you have installed on your Mac. The days of having to navigate to the Applications folder to launch a non-dock app are over, just load the Launchpad and you can see all your apps in one place.

Redesigned Finder & Core Apps

Finder has undergone a small makeover as well, most notably losing the colored buttons in the sidebar and adding a few useful features. “AirDrop” lets you copy files to any other Mac on your network’s Downloads folder, and “All My Files” shows you a handy view of every file on your machine, sorted by type of file. Other than that its the same old Finder that we’re used to, and some may be disappointed that much-wanted features like tabbed file browsing are left out of this one.

The core apps in OSX have also undergone a bit of a makeover, most notably, which now sports a dual-column layout like Mail for iPad, and also features threaded messages. GMail users have been enjoying threaded messages for years, so its nice to finally have desktop mail apps supporting this very important feature.

iCal and Address Book also feature much-needed updates, making their interfaces much nicer on the eyes and adding a few new features, but nothing huge.

Full Screen Apps, Auto-Save and App Freezing

Taking more cues from iOS, 10.7 Lion has a few features that we are used to on our mobile devices. A button in the top-left of every supported app window allows you to send that app into full-screen mode, where the app will take up the entirety of your Mac’s screen. Once you full-screen an app its window becomes a Space, and you can flip between that app, other full-screen apps, and your desktop spaces normally. I can see this being very useful for media apps such as Aperture, where you could edit some photos in full-screen mode and then switch to your desktop and do something else without having to exit full-screen.

I wrote this post in Safari full-screened, and much enjoyed the large workspace experience along with the ability to switch to doing something else quickly without exiting full-screen mode. I just swipe over to my desktop space or use Mission Control to select the window I’d like to switch to.

Safari running in full-screen mode

There’s also new APIs in Lion for applications auto-saving documents and “freezing” their state–meaning if you quit an app its state will be saved, and the next time you open the app it will be right where you left it. Apple introduced this as a substitute for full multitasking in iOS, but it works even better in the desktop environment. If you accidentally quit Mail in the middle of writing a message, when you reopen it will be right there ready to be finished. I haven’t had a ton of chances to use this feature, as no third-party apps support it yet. Once more developers get their hands on Lion I can see both of these features being very useful.

Overall it looks like Apple is heading in a touch-based direction with Lion, and its an absolute pleasure to use with a trackpad. Once the inevitable touchscreen Mac is released I think Lion will fit wonderfully.