Apple has posted a chart on their developer center showing that iOS 7 adoption, as measure by connections to the App Store between November 25 and December 1, 2013, has reached 74%. That means, in the less than 3 months since launch, very nearly 3 out of every 4 iPhones, iPod touches, and iPads that connect to the App Store are now running the latest version of Apple's mobile software. 22% are running iOS 6, and only 4% are running iOS 5 or earlier.
For developers, it should make targeting iOS 7 a no-brainer. For customers, it should mean more stuff that takes advantages of the new frameworks in iOS 7. For Apple, it should mean the combination of a focused platform with free, non-intermediated software updates is paying by not only letting them move quickly towards the future, but by bringing their install base along with them, rather than having to drag them behind.
Win. Win. Win.