Apple has announced the release of the developer preview of the next version of its OS X operating system - Mountain Lion - on Thursday, giving developers and Mac users a sneak peek into what is to come when the new OS launches in the summer.

Key to the new OS is a number of new features that further merge the company's two operating systems "Mac OS X" and "iOS" for the iPhone, iPad and iPod touch even closer together.

iOS-fication of the desktop, started by Lion, really is in full swing as we found out, having already been demoed the new developer preview from Apple ahead of the official announcement.

Key to the merging of the two operating system is that OS X will take on several features previously found in iOS including iMessage, Reminders, Notes, Game Center, Notifications, and heavily integrated iCloud support that allows users to share data and files quickly within the Apple eco-system of devices in their home.

But it's not only new apps that will be heading to Mountain Lion, but also a more iOS approach to apps.

Apple hopes to simplify everything by also using the same terminology on the desktop as it does on the mobile platform. Address Book becomes Contacts while iCal becomes Calendar, to mirror the iPhone offerings of the same name.

As with iOS Twitter will also play a major part in the new operating system, being "baked in" in the same way it has been on the mobile devices from Apple.

Users will be able to share links, images, video and more instantly with Twitter, Flickr and Vimeo at the press of a button rather than having to cut and paste or open separate applications.

AirPlay Mirroring also gets a look in in Mountain Lion with users able to wireless stream their desktop to a television with a little help from Apple's Apple TV.

But it isn't just about the iOS-ification of Mac OS X. It has new features and new apps to that can't be found on the mobile platform.

Apple is introducing a new digital signature feature for developers, called Gatekeeper to try to stop Malware, while those in China get greater support for native services and the Chinese language.

OS X also features new graphics features for developers to take advantage of and better support to allow developers to include an array of gesturers in their apps, suggesting that plenty of exciting things could be coming in the future from developers keen to take advantage.

Our time was brief with the new OS and we are already planning a second, more in-depth look in our own time with the next generation operating system, but it is clear that while there isn't any major groundbreaking new features - as we've seen with Apple operating systems in the past - this is Apple getting their "ducks in row" and simplifying the whole process. Apple are using Mountain Lion to ditch a several strange anomalies that have appeared over years of tinkering and no longer match the more popular iPhone and iPad. That, to our minds, is a good thing.

Whether it is simply calling iCal Calendar or moving the software updates from a dedicated service to the Mac App Store to make it more logical, anything that makes using your computer easier is more than welcome in our book.

We especially like the new ability to play games against our iPhone or iPad touting friends via the desktop with the addition of Game Center and streaming our desktop to our TV via Apple TV is going to be great fun too. 

The new operating system might not convince you over and above any other reason you've already thought about to buy a Mac but by Jove, when you do make the plunge if you are coming from an iPad or an iPhone, it will be even easier to understand tham it ever has been previously.

OS X Mountain Lion is expected to be released in the summer. 

- OS X Mountain Lion: 10 hot new features preview shows us coming