Released only about seven months ago, Lion was the first version of Apple's Mac OS X desktop operating system to reflect a strong influence from iOS. Today the Cupertino-based company is teasing us with a peek at the next major update to OS X, dubbed Mountain Lion, releasing a developer preview that brings a few more features and apps from the iPhone and iPad to the Mac.

As its name suggests, it's a continuation of Lion packing lots of small changes and optimizations rather than being a complete overhaul of the OS – not unlike the transition from Leopard to Snow Leopard. With this upcoming launch, Apple is reportedly moving OS X releases to a yearly schedule.

Scheduled for public release in late summer, OS X 10.8 Mountain Lion is still in an early development stage, but far along enough for Apple to begin highlighting a few key features. Among them is a new Messages app which replaces iChat and adds iMessage support to Mac, while continuing to offer access to AIM, Jabber, Yahoo! Messenger and Google Talk. A public beta of Messages is available for download right now.

The application enables Mac users to text chat via iMessage with iPhone, iPad and iPod touch users. You can start an iMessage conversation on your Mac and continue it on another iOS device, send photos and other attachments, or launch a FaceTime video call to bring the conversation face-to-face.

Keeping up with the iOS-like additions to OS X, Apple is also bringing Notification Center to the Mac, providing a central location for alerts from apps such as Mail, Calendar, Messages. Reminders, Notes, and Game Center apps are also being ported over to the desktop and will sync seamlessly across your various iDevices.

AirPlay Mirroring is another welcome addition for those wishing to beam a 720p video stream of their Mac's screen to an HDTV connected to Apple TV. Users will be able to stream content from iTunes, but apparently some content will be blacked out on the Mac while playing back on the HDTV due to copyright limitations.

Like it did with iOS 5, Apple is adding full Twitter integration in Moutain Lion, meaning that users can tweet directly from Safari, Photo Booth and other apps. Lastly, there's also a new security feature called Gatekeeper that will give users more control over which apps can be downloaded and installed on their Macs.

Overall, Mountain Lion already sounds like a solid upgrade and another step towards Apple's plan to bring iOS and Mac OS X closer together. One feature that's notably missing is Siri, although Apple says that more than 100 changes and additions are coming in OS X 10.8 so perhaps they're just keeping it under wraps.