Here's something you don't see every day: Apple (Nasdaq: AAPL) passing on the opportunity to host an announcement event that inevitably always turns into a media frenzy. Earlier this week, Apple quietly showcased the next relatively major upgrade to its desktop operating system, Mac OS X.

There was no big gathering or press event -- just a press release and a new page on its website that details some of the new features to expect, while a preview was released to its army of developers. The next version will be 10.8 and follows the feline nomenclature with "Mountain Lion."

Back to the Mac
In comparison, when Apple unveiled OS X 10.7 Lion, it hosted a small "Back to the Mac" event to show off all the new features. At the end of the presentation, Steve Jobs' customary "one more thing" was the redesigned MacBook Airs, which have promptly taken off in popularity, leading Intel (Nasdaq: INTC) to respond with its Ultrabook reference designs.

Source: Apple press release.

Lion brought a lot of the features of iOS back to the Mac, and Mountain Lion continues that trend even further. Cupertino is adding yet more characteristics of iOS, like iMessage, AirPlay Mirroring, Game Center, and Notification Center, into OS X. The company is also introducing a new feature called GateKeeper, which is being presented as a security feature. It allows you to block installation of apps outside its Mac App Store, which not so subtly encourages you to shop for software in Apple's 30%-cut environment.

Another thing that stood out was that Apple highlighted new features specifically geared for China, including built-in integration with popular Chinese Internet services such as Baidu, Youku, Tudou, and SINA's Twitter-esque Weibo. Still need more evidence of the region's importance and growth potential? I don't.

A few words, Mr. Cook?
In an interview with The Wall Street Journal, CEO Tim Cook said, "We see that people are in love with a lot of the apps and functionality [in the iPhone]. So, anywhere where it makes sense, we are going to move that over to Mac." He also said he already considers iOS and OS X effectively unified but that each has "incremental functionality."

He was asked about the possibility of having iDevices and Macs all running on the same processors, which is a clear reference to the rumblings that Apple has considered putting its custom-designed ARM Holdings-based chips into Macs, although it doesn't seem likely any time soon (as Intel breathes a sigh of relief). Cook simply responded: "We think about everything. We don't close things off."

On the other hand, he virtually confirmed that Siri will make its way to the Mac, as he smiled and deflected the question. The possible inclusion of Siri in all future Apple devices could potentially be a boon to Nuance Communications (Nasdaq: NUAN) as the back-end recognition provider, but there's still a lot of "complexity" with that relationship that leaves us guessing.

Everyone's doing it
There really aren't any revolutionary new perks or game changers, but rather a continuation of the evolutionary trend that Lion started with the convergence of operating systems. Desktop and mobile operating systems are quickly heading toward the same destination, and while Apple may have started the movement with Lion, it's not alone.

Microsoft (Nasdaq: MSFT) unveiled Windows 8 late last year, and there was no hiding its clear inspirations and takeaways from Mr. Softy's own mobile Windows Phone OS. It made heavy use of the Metro design style that Windows Phone had embarked with, and it was obviously designed with touch interactions in mind, as it will be Microsoft's tablet OS. Once Windows Phone 8, codenamed "Apollo," comes out, expect even more similarities.

Meanwhile, Google (Nasdaq: GOOG) hasn't made much of a dent with its own Chrome OS, which is primarily geared toward netbooks because of its heavy cloud reliance. On the other hand, Android continues to be one of the top mobile operating systems, and there has been talk that the next major version of Android, 5.0 Jelly Bean, will borrow some functionality and features from Chrome OS.

What we're seeing is a major convergence of operating systems being pursued by the three biggest players that define the vast majority of our computing experiences. That's a massive shift, and it's one that investors won't want to miss out on. The mobile revolution is set to become The Next Trillion-Dollar Revolution, and The Motley Fool has just released a new special free report on one company that will help power the revolution, while also banking on China's explosive growth. Get the free report now.