Interestingly, a Danish Professor predicted that the external iPhone 4 antenna would not perform as well as claimed by Apple. What this Snafu really means for Apple and AT&T has yet to play out, but those following iPhone stores know, the redesign was in response to poor call quality in the 3Gs design.
Apple has said 1) we the public are holding the iPhone 4 incorrectly (as if my 40 years of phone usage has been an exercise in futility) and 2) they will be patching their software to address this issue, however... this does not appear to be a software issue, but a fundamental antenna physics problem. What this means is everyone will need to buy a case for their phone to solve an Apple generated problem (and in turn make even more money for Apple).
"We strongly recommend you go and read it right now, but here's a taster of the beautifully worded explanation: "[The aerial design] would be fine... except for one design component. The user. Users have hands and hands are made of flesh, which to a radio wave looks like a big bag of conductive saline solution. As submariners know, if you surround an antenna with a large lump of salty water, it stops working: it's shielded from the outside again, and its electrical length will change dramatically."