According to John Gruber, a well informed Apple insider, Apple knew about the external antenna issues on the iPhone almost two years ago. In a post giving his thoughts on Mark Papermasters departure from Apple, Gruber said that the company filed a bug on the issue and had plenty of time to find a solution.
One last tidbit from an informed source: the bug on the touching it wrong signal loss issue was filed two years ago. This is not a problem they didnt catch, or caught too late. So, on the one hand, clearly the fundamental antenna design predated Papermasters time at the company.
But on the other hand, there was plenty of time to find a solution to the problem. I.e., its not that Apple should not have used an external antenna. Its that it should have been even better, Gruber wrote. It still remains unknown if Papermasters departure from Apple is related to iPhone 4 or his relationship with Steve Jobs (or maybe both).