Even though Ice Cream Sandwich (Android 4.0.3-4.0.4) was released nearly a year ago and Jelly Bean (Android 4.1) about three months ago, Gingerbread (Android 2.3-2.3.7) is still the top OS among Android users. Version 2.3 of Gingerbread still accounts for almost 56% of users, while Ice Cream Sandwich is now up to 23.7%. The latest offering from Google, Jelly Bean, is only at 1.8%. The low rate for Jelly Bean is not surprising since there are only a handful of devices that have been released that are capable of being upgraded to it (e.g. Galaxy Nexus, Nexus S and Nexus 7). The adoption rate is expected to jump significantly once popular devices such as the Galaxy S III and the HTC One X get upgraded. It was recently reported that Samsung has started to roll out Jelly Bean to its devices in Europe while HTC smartphones will receive the update later this month.
In the Apple world updates to the OS are supported by most of its devices, only the older iPhones were not capable of upgrading to iOS 6. As a result, the adoption rate of the new mobile OS by iPhone users was already 17% after only 24 hours and now today that rate is at 60% in Canada and the US.
Source: Mobile Syrup