If it had instead said "full binary compatibility with DARWIN", or iOS 5 Darwin, it would have been clear.
And, by the way, if you hadn't said "go away" to people who wanted app compatibility, I might have been less annoyed by the deception. OF COURSE people want app compatibility. It's the core coolness of the project's potential! And maybe someday you'll get a crowd of people around you that can help achieve that. But telling them to go away isn't going to help.