what should happen, most likely with other phones, is that the range should be evenly distributed so that a drop in 1 bar is a drop in 1 bar. because iPhone 4's distribution is weighted/biased towards the top half of the spectrum, it fails when you cross the threshold. This "feature" seems like it was introduced in OS 2.1 back in '08.
You also can't avoid drops in signal when putting your hand over it -- this happens with every phone. just iphone's visual representation algorithm makes it seem far worst than it really is, and they will fix the way it displays in the next version.
EDIT: Why the downvote? Gruber even stated that the issue is the introduction of the biased bar meter. The exposure of the antenna just highlights the issue when you're at the threshold between 5 bars and "other".
EDIT: again, why the downvote? To quote apple's letter: "To start with, gripping almost any mobile phone in certain ways will reduce its reception by 1 or more bars. This is true of iPhone 4, iPhone 3GS, as well as many Droid, Nokia and RIM phones."
"..this mistake has been present since the original iPhone"
24 dB of loss is a staggering amount of power. Watt for watt, it means about 1/250 of the signal power is actually available to the phone's radio hardware when you hold it the "wrong way."
That is simply not acceptable regardless of what various blogs, experts, and apologists say. The fact that it was necessary for Ars Technica to hack the phone to obtain a quantitative figure at all is also damning.
I ask because -- per Anandtech's numbers -- the Nexus One can lose up to about 30% of signal strength depending on how you hold it. Which, while less than the iPhone 4 (which can lose up to about 38%), is still a rather large issue.
At any rate, the question stands and I'll just rephrase it in terms of just the dB numbers: is 17.7 dB OK but 24.6 dB not? If so, on what basis? If not, where's the outrage over the Nexus One?
And that's without getting into questions like "is it OK to lose a bit more signal if the ability to keep functioning on reduced signal has improved enough?"