The 2 and a half year old Android 2.2 Froyo is still hanging on with a respectable 9% share, putting it ahead of newer versions of Android like 3.0/3.1/3.2 Honeycomb. It's still close on the heels of the newest version of Android, Jelly Bean, which now has 10.2% of the market.
Note: This info doesn't reflect all Android devices, just the ones which access Google Play. So there is some unknown number of devices out there which run Android but aren't factored into these stats. Examples include the Kindle Fire, Nooks, and a bunchaton of budget Android tablets.
The year-old Android 4.0 Ice Cream Sandwich is in a solid second place with a 29% share, but the single most commonly used version of Android is still 2.3 Gingerbread. As a result of new devices activated over Christmas, this version of Android is no longer running on half of all Android gadgets. No, it's down to 47.2%.
The continued dominance of the older versions of Android are something of a problem for the platform. It's a source of frustration for app developers who want to make the best app they can, but are unfortunately blocked from using features found only in the later versions of Android. It's also frustrating to device makers, but not just because the older devices are still in use.
The bigger problem is that Android tablets running Android 2.3, 2.0, and even the so-old-it-should-be-getting Social Security Android 1.5 Cupcake are still sitting on store shelves. They're still being sold as new devices; I can say that for a fact because I am still seeing commenters show up and ask questions.
This is a problem which is likely going to continue to grow worse as new versions of Android are released. Developers are already having to write off the early versions of Android, and that leads to the unfortunate situation of new owners finding out they can't run current apps on their new device.
All this adds up to Android having the reputation that app support is miss, hit, or miss, and the only one who benefits from that is Apple.
Apple's limited hardware set makes it a lot easier for developers to support, and it also makes it easier for Apple to release firmware updates. According to Chitika new versions of iOS are adopted rapidly, with iOS6 hitting the 50% in less than a couple months.
Google only wishes they could match that.