Trending: NASA says much-anticipated meteor outburst could be a bust for the West Coast

Apple is famous for the tight end-to-end integration of its products — controlling the operating system, applications, services and hardware. But increasingly the company is extending that integration across its different devices, as well. And Mountain Lion, the next major version of the Mac operating system, takes some major new steps down that path.

In a surprise move, Apple released Mountain Lion as a developer preview this morning, saying it will be available as an upgrade for Mac users this summer. Many of the features will sound familiar to iPhone and iPad users, including a new Game Center, Notes, and a Notification Center, plus Twitter integration and other features for quickly sharing items.

But it’s not just about making OS X more like iOS — it’s about making the iPad, iPhone and Mac feel more like a unified experience.

That was already starting to be the case with last year’s debut of iCloud, but Mountain Lion takes it to a whole new level.

Exhibit A: In addition to the developer preview, Apple issued a public beta of a new Mac app called Messages, which will replace iChat for instant messaging on the computer while adding text messaging, so long as the devices you want to communicate with are running iOS 5.

My experience trying Messages this morning made the extent of the OS X and iOS integration clear.

After I downloaded the Messages app on my Mac and made some tweaks to the settings on my iPhone (changing the “Caller ID” in iMessage to my Apple ID email address) messages sent from my Mac to another iOS 5 user were mirrored in both the Messages app on the Mac and iMessage in the iPhone — allowing me to switch back and forth between the Mac and the phone to carry on the conversation.

Will Apple release a Messages app for Windows PCs to talk to iPhones? Don’t hold your breath. By turning the iPhone, iPad and Mac into a unified experience, Apple can leverage the popularity of its mobile devices to give its traditional computer business even more of a boost.

In other words, this is where Microsoft really starts to feel the pain of its minimal tablet and mobile phone market share. With the promise of a late summer release for Mountain Lion, it will be fascinating to see if it comes before, after — or at the same time — as Microsoft’s Windows 8.

For more reading about the upcoming Mac OS X revamp, MG Siegler has been using Mountain Lion and has a good rundown of the features on TechCrunch. John Gruber also has a great behind-the-scenes story on Daring Fireball. Also check out Jason Snell’s hands-on for Macworld, the official Apple news release, and a ton of coverage on Techmeme.

Like what you're reading? Subscribe to GeekWire's free newsletters to catch every headline


Job Listings on GeekWork

Find more jobs on GeekWork. Employers, post a job here.