Matt Gemmell, on the question of how far back iOS developers should go in terms of supporting older releases:
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.
It’ll be interesting to see how iOS 5’s long-awaited over-the-air software updates affect the new OS adoption rate.