[wlesieutre]

There are very different degrees of fragmentation. An iPhone 3gs is 5 years old (launched in June 2009) and supported the newest version of iOS for more than 4 years (until iOS 7 launched in September 2013).

Contrast that with Google's Nexus One, which kicked off their Nexus program of well supported phones. It launched in March 2010 with Android 2.1, and got its last update to Android 2.3.6 in September 2011.

So for the iPhone: 4 years of support, and that's a typical experience.

For Android: 1.5 years of support, and that's on a good example with support managed directly by Google as part of their "look we can do long term support" program.