By Kevin Kelleher, contributor
FORTUNE – In a world increasingly going mobile, platform is destiny. The operating system will determine who rules -- or at least who has a seat at a lavish feast. Whether manufacturing phones or tablets, selling mobile ads or developing apps, the operating software running the show will determine how well it succeeds.
Although there are several mobile platforms in the market or in development, only three really matter: Apple's (aapl) iOS, Google's (goog) Android and Microsoft's (msft) Windows Phone 8. Each company creating these platforms have taken to manufacturing devices -- Google and Microsoft recently, Apple years ago -- to strengthen their software, whether through patents or device design.
And all three companies are reaching out to developers, who build the apps that in turn draw in consumers. Over the past several weeks, Apple, Google and Microsoft have held conferences for software developers, introducing new software, new devices and new strategies -- all aimed at building or maintaining each company's respective market share.
Together, they show an industry where large, cash-rich companies are vying against each other and rapidly innovating. Here is a quick look what Apple, Google and Microsoft announced in smartphone and tablet innovation, and where their relative strengths and weaknesses are.
What's new: At its Worldwide Developers Conference in early June, Apple offered details on iOS 6, expected on new iPhones this fall. The upgrade will have 200 new features, many not very big (new dialer layout) but others that are notable: a reply-later option for phone calls you can't take immediately, Facebook (fb) integration baked into iOS for seamless sharing of all your iPhone activities, Facetime over cell-phone networks, a Passbook app that could turn the iPhone into a credit card and the introduction of Apple's impressive new maps app.
While the biggest announcement from the conference was the Macbook Pro with Retina Display, Apple also provided details on its Mountain Lion, which inches iOS and the Mac operating software closer together. Like Microsoft, Apple envisions the lines between laptops and tablets/smartphones blurring. It's taking Apple longer to merge the two, but that slower approach may yield fewer glitches.
What it means: These announcements represent a lot of incremental additions that add up to a substantial effort to keep Apple at the innovative edge of the mobile world. No one is going to ditch their Android phone just to they can use, say, Passbook or Apple Maps, but the iPhone has always been about a compelling user experience, and no one has surpassed Apple on this front yet.
Much will depend on how alluring the coming iPhone 5 will appear against offerings from Google and Microsoft. Many iPhone customers have been waiting for a version that will work on high-speed LTE networks -- an upgrade that will make many apps more powerful. For now, this is Apple's race to lose.
What's new: The biggest surprise in tech this summer has been Microsoft's move to design and manufacture its own devices, a practice it's been content to let Dell (dell), HP (hpq) and others handle for decades. But Microsoft wanted to get a Windows tablet right, and so it unveiled the Surface tablet, a move that almost nobody was expecting.
With Surface, Microsoft is channelling its inner-Apple: adding a subtle, intuitive hardware design -- such as the keyboard built into the tablet cover -- to enhance the usability of the operating software. The Surface won rave reviews from those who tested it, even though some said hands-on tests were too limited to be useful. The device could make Microsoft a player in tablets, especially if pushed in Microsoft's new retail stores.
The software inside the Surface also promises to be competitive with Android and iOS. Windows Phone 8 will support dual-core chips, multiple screen resolutions and near-field communications used in wireless e-commerce transactions. It also offers a Passbook-like wallet and a native map technology.
What it means: Mobile OS has been a two-horse race, but Microsoft may just give Google and Apple a run for their money. Microsoft has shown it's willing to take bold steps to stay competitive in personal computing, even if it means writing an OS from scratch or stepping on the toes of its loyal partners.
Just how strongly Microsoft can compete against Google and Apple in mobile platforms remains to be seen. When Windows 8 arrives this fall, will the integration of PC and mobile software be buggy or seamless? Will developers enjoy working with the software enough to offer Microsoft appealing apps? These are big questions still facing Microsoft.
What's new: As expected, Google announced at its I/O developers' conference the latest update to Android software: version 4.1, aka Jelly Bean. The upgrade will be available before iOS 6 or Windows Phone 8 for Galaxy Nexus and Nexus S users. Those updates will keep the small fraction of Android owners who will get Jelly Bean happy.
Jelly Bean will improve the voice-dictation features on Android phones, offering Siri-like direct answers but also offering the option to see Google search results with a simple screen swipe. Voice recognition will also work offline. Another new feature is Google Now, which considers data like time, location and personal history to, for example, offer alternative commuting routes or nearby restaurants that may be of interest.
But like Microsoft, Google is innovating in hardware as well, and some of the bigger innovations are here. Google introduced the Nexus 7, a seven-inch screen manufactured by Asus that will sell for $199 and offer a better experience than Amazon's Kindle Fire tablet for the same price. And it impressed with the spherical Nexus Q, a multimedia streaming device that is integrated with Google Play. But the big impact came from Google Glass, a future product that drew buzz mostly for its dramatic skydiving presentation.
What it means: Android powers more phones than iOS but it suffers from fragmentation. Only about 11% of Android phone users are using the latest version of the software, so many won't be able to see the benefits of Jelly Bean for a while. But that's not keeping Google from pushing into all kind of new directions.
While most of those directions are promising, they aren't assured success. With the Nexus 7, Google is going for the low-end of the tablet market, appealing to consumers who don't want to pay three times that much for an iPad. Nexus Q is a small step into the living room. And Glass shows that Google has one fixed squarely on the future, where augmented reality and new computing devices could become the norm.
For all the bickering and patent scuffles that can occur among these three companies, the competitive drive to stay ahead in the mobile economy is pushing all three to take risks and push new ideas. Of course, the best ideas will be adopted by all companies, prompting them to new innovations. In contrast to patent lawsuits, that kind of competition is what keeps the tech industry moving forward.