Matt Gemmell, after reading my iOS stats:
But when people ask how many OS versions they should support in their new app (which they do, often), they’re not looking for a common-sense and at least reasonably evidence-based answer like that. Instead, they’re looking for this answer:
It’s OK to support only the newest version of the OS.
That’s what they want to hear. Honestly, I think it might even be true, but I know that we all want it to be true. So to help you to convince yourself, here are the relevant arguments conveniently collected in one place.
If I were launching a new app today, I’d make it require iOS 5. I’d save a lot of work that way. But here’s another data point.