Ask HN: How long do you support iOS4 before moving to iOS5?

Personally, I pay much more attention to what is being deprecated, and plan my upgrades with that trailing horizon in mind.

Forget about if the newest release of a class is easier for me (the developer) to use, if it doesn't deliver a significant performance advantage to my end user, I ignore the new features and stick with the oldest version still supported.

Obviously I couldn't do that with an entirely new functionality like iCloud, but for something like MPMoviePlayerController? Forget about it.

I know it can get annoying to check the iOS version before every method call, but well designed code can minimize this greatly.

Personally I'll be supporting iOS 4 until a good bit of the stuff I use in it is deprecated by Apple.