iOS devices have, on average, reached 10% version share 300 times faster than Android versions, 30% share 19 times faster, and 50% share 7 times faster.
It will be fascinating to see how these numbers change now that iOS features wireless updating.
In a way, I think that iOS buyers are paying to be on the cutting edge of software. Android OEMs have been one-upping each other on the hardware front (the Android spec race has reached almost ridiculous proportions), but this is a shallow, easily-duplicated strategy. An ecosystem that has been developed instead with a software focus affords many advantages that are not easily mimicked: ease of development, users being able to learn about apps and the OS from friends without the frustration of fragmented device capabilities, and more.