Android Jelly Bean has been around for two years now, available on devices from multiple OEMs, and with devices now being launched 4.1 or 4.2. There is a lot of talk of Android 4.3 Jelly Bean also being released at some point this year, and rumours of the Key Lime Pie (Android 5.x) also being launched this year.
Windows Phone 8 is also available on devices from different OEMs, with Nokia Lumia devices being the most talked about. HTC, Samsung and Huawei also have their own devices out and about.
Talk of Windows Phone Blue, or 8.1 has also been bandied about, with an expected release alongside Windows 8.1. Current devices span the market, again from a variety of OEMs, with the high end Nokia Lumia 925, or the low end Lumia 520.
BB10 is unavailable on all new BlackBerry devices, the BlackBerry Z10, Q10 and Q5. Being a whole new OS, it is unavailable on previous BB7 toting devices.
As for BB10 on the PlayBook, your guess is as good as our at this point, with BlackBerry's 2012 annual conference stating that it would make its way across, although 12 months later, there is still no update. Being an all new OS, BB10 is now available on the BlackBerry Z10, BlackBerry Q10 and announced BlackBerry Q5.
The iOS7 launch is arguably as important to the Cupertino-based firm since Steve Jobs first took the stage in 2007 to launch the original iPhone.
A number of previous devices (iPhone 4, 4S, 5, iPad 2, 3, 4, iPad Mini and iPod Touch 5th generation) will be getting the update, with the OS also being a major precursor to the upcoming iPhone 5S/6, iPad 5 and iPad Mini 2.
Apple therefore has a very large existing customer base ready to upgrade, with those on earlier iDevices also potentially looking to the launches of the next line of products. iOS is also highly successful in the business market, as well as the personal market.
It is therefore almost impossible to say that iOS7 will be a flop, after all the trouble that Apple maps gave iOS6, it is still very popular. Android is Apple's biggest worry, with Windows Phone 8 and BB10 making strides through the mobile market, yet still not as firmly established.
Android handsets are still the most popular on a world wide scale, but only just over a third are actually running Jelly Bean, with the fragmentation the major negative point against what is a highly versatile platform.
iOS7 will be massive, but don't forget it is really just the first OS refresh to launch this year, with Windows Phone 8.1, Android 4.3 Jelly Bean and/or 5.0 Key Lime Pie likely to arrive later in 2013. Expect to see the competition really heating up.