It also may be significant that many people who own an iPhone 4 are deliberately "testing" it and trying to attenuate the signal. That's the first thing I did

It also may be significant that many people who own an iPhone 4 are deliberately "testing" it and trying to attenuate the signal. That's the first thing I did after turning on mine. With the 3GS, most people weren't aware for how to attenuate the signal and weren't trying to. In my opinion, that "testing" alone could account for the increase in iPhone 4 dropped call rate.