I'm just now starting to read over this thread, and I've noticed the same issue with my 4. I realized however, that it only drops reception if i hold it in my left hand. In my right hand, it's fine.
But this is really unacceptable for a $600 gadget. Hope they find a fix.. It's so bad, that even when i'm talking ON THE PHONE while holding it in my left hand, I lose reception... what a mess.
Is your left hand much larger than the right?