iOS users installing iOS 5.1 quickly
It took iOS 4 a month to reach 50% usage based on web traffic. While that figure can't be directly compared to the figures that Smith compiles from app usage, it does show that adding OTA as an option for installing updates made the adoption rate climb faster than in the past. Smith adds that the current adoption rate for iOS 5.1, at 61% of those using his apps, just about equals the rate that Android users have had with Android 2.3. Android 4.0 is currently used by just 1.6% of Android users after 5 months. But the blame for that appears to be from the manufacturers and carriers rather than the end users..
Apple started OTA updates with iOS 5 and the only other update to allow such installation was iOS 5.1.