I just flicked through the keynote for the iPhone 4 again to find a point where Steve would lose reception. I found at 1.08.08 (h/mm/ss) that Steve grabs the phone in his left hand for about 50 seconds and doesn't loose one bar of signal. However, when he has the phone in his right hand he seems reluctant to grap it properly and just lets it float there. It is possible that Steve had a build of iOS 4 that would just display full signal all the time. I'm still hoping its a software glitch, because it's outrageous to say, "Just avoid holding it that way..."