On the software side, apparently they use API names that are disguised.
For example, still image stabilization was one of the new features of the iPhone 5S camera announced today. And yet, iOS 7 beta has been out for a while. They would have had to have development support for that feature somehow in the OS that thousands of other developers also need to get their hands on.
For example, here’s an API diff. The other answers to the question have some interesting stories.
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