Uncalled for sneering in the quoted post. I'll edit the insults but the factual issue raised is valid.
BGR has a more useful write-up,
Holding the iPhone 4 affects the antenna, degrades cellular signal? � Boy Genius Report but unfortunately the fix suggested in comments (plastic film insulator) is unlikely to work because inductive and capacitative coupling will still have a huge impact.
I was waiting for the light to come on about this, the problem was obvious to any RF engineer as soon as the design was published. I would have no hesitation in sacking the designer, or resigning in shame if it was my design. Putting it simply, broken by design.
My advice to anyone affected by the problem is to reject the phone and return it as "not fit for purpose" and also a potential health risk by emitting RF radiation directly into the user. Simply touching the antenna with a hand or other body parts will cause the phone to increase its transmit power to compensate, with even greater RF exposure and reduced battery life.