If you haven't been following, the design of the antenna makes is such that you can short-circuit the antenna if you hold wrong. Even in areas with good to great coverage, this can make you drop calls and have weak or no reception.
Poor reception by AT&T is another real problem, but not at issue here.
Edit: More to the point, the grip that causes perhaps the greatest attenuation of signal is one of the more comfortable, natural grips for the phone. The effectiveness of any phone's antenna can be reduced if you hold it right. Most phones are designed so that the comfortable, natural ways to hold the phone minimally interfere with the signal.
Sure. Apple don't seem to acknowledge that their design is stupid anywhere. People will hold phones how they want to hold phones. It's ridiculous for anyone to claim they're holding it 'wrong'. If they're holding it 'wrong' then apple designed it 'wrong'.
I just tried holding my Nexus One (UK) in different ways. I was able to squeeze it from 4 bars down to 3, but nothing else :/