According to the announcement, the NDA was in place in order to protect includes many Apple inventions and innovations included in the iPhone OS. In fact, the NDA’s only purpose was to offer a supplemental layer of legal protection for the iPhone, so the device wouldn’t end up “being ripped off by others”.
One might feel free to bet that Apple’s grip was aimed much further with the NDA in place. But even a secret-loving company such as Apple had to give up some ground eventually:
“However, the NDA has created too much of a burden on developers, authors and others interested in helping further the iPhone’s success, so we are dropping it for released software. Developers will receive a new agreement without an NDA covering released software within a week or so.“
Last but not least, Apple stressed out once again that unreleased software and features will remain under NDA until they are released.