I'll preface this by saying please don't shoot the messenger. I'm just trying to share my experience in the hopes that it might help someone else. After seeing the YouTube video yesterday, I found that the signal loss issue was easily reproducible on my iPhone 4. If I cupped the left corner in my hand I could watch it go from full bars to "Searching..." in about 30 seconds. I was annoyed, but it wasn't a dealbreaker for me as I usually don't hold my phone like that anyway. For unrelated reasons, today I was checking out the microsim slot and put my finger on it and slightly pushed. I felt it slide in just a bit further to the point where it was entirely flush with the side of the phone. It wasn't exactly "sticking out" before, but I guess it had shifted out slightly during packaging and shipping. Long story short, ever since pushing my SIM card in entirely, I've been unable to recreate the signal loss issue. I've cupped that corner in my hand for over a minute without encountering any drop in the bars. I've also made a call on speakerphone while covering the area in question with no ill effects. My iPhone seems to be "cured". Hopefully this information might help someone else out there. If your iPhone 4 does have this issue, try pushing in on your SIM card, or even removing it and reinserting it to reseat it. It's worth a shot.