Watch and listen closely as YouTube user and iPhone 4 owner Mike "Mself27" demonstrates a striking call quality issue using nothing but a finger. Call quality suffers at about 2:45. A simple software fix, he contends, might not be enough.
A little more background, courtesy the video summery:
Demonstration of the new iPhone 4 showing problems with TRANSMISSION as well as reception. Note the substantial signal degradation (and subsequent audio dropout) at 2:45-2:50 and 2:58-3:01. By simply MOVING MY FINGER along the side of the iPhone, I can get the call to drop signal and audio!!
The effect his finger has when moved across the seam is undeniable. [YouTube]