Gizmodo has the story on this and claims that multiple readers who have exchanged an iPhone 4 recently for a new one are claiming that the new ones no longer have any signal drop when using the "death grip", a term famous for holding the iPhone in a certain area that would cause a signal drop. Gizmodo has now around ten reports from readers all saying that they've seen a dramatic improvement in signal drop, dropped calls, and call quality all while using this death grip. One sample report is below and to view the full story, check out Gizmodo's article. They reiterate many times that this isn't solid proof of a fix just yet, but it's certainly worth noting.

I had the problem with my iPhone 4 experiencing the "Death Grip". I took it back to the store and complained about "slow data speeds" as I knew the "death grip" wasn't a "valid" enough reason for them to exchange the phone. My first phone no matter, how great the signal was, the "Death Grip" was in full effect as I could make the phone go to "searching" with in a few seconds. This new unit (mind you has ZERO cosmetic differences) is perfect. The "Death Grip" is totally fixed an fluctuates no more than 1 bar in a bad signal area. Something is definitely different with this phone as IT WORKS!

At home we have a tower that is literally about 600 feet away from my house. The first phone I could death grip it and make it go all the way to searching within 20 seconds. This new one goes from 5 full bars to 4 bars then after a few seconds will kick back to 5 bars. That is without the bumper just raw phone in hand. I am in Arizona.