In all cell phones, the bars you see are calculated approximations of signal strength over time. The iPhone 4 added quite a bit more complexity to the antenna system in order to get better reception, so probably the bar calculator routine wasn't modified accordingly.
HTC had a "problem" like this a while back. People complained about low bars, but the signal was still good. HTC changed the way the bars were calculated, and customers were happy even though they had the same exact signal they had before.
But they said it was always a problem and not a new issue.
That's pretty funny. I was talking with a fellow in my office who got one of the new iPhones about it. As far as I'm concerned, anyone who uses an iPhone without a protective cover is just asking for trouble. The thing just feels too darn fragile. If I had one, I'd be scared to death of dropping it and having the screen shatter. Of course, that doesn't excuse the silly excuse for quality control that let the phones make it to market with the problems they had, whether they are real or not. From what I understand, they didn't notice it because the majority of phones they were testing had a cover on them to conceal the fact they were the new iPhones, but that really isn't a good excuse IMO.
You hit it right on the nose, antiRepublicrat...
The problem is how they have (always) set the levels between bars, artificially making it look like 5 bars even when you've lost more than 20% of the max signal. Interval determination can be tricky when it comes to some things, such as shading (because the human eye doesn't see linear changes in shade in a linear manner). But this, however, seems to be an intentional trick they've played...but with the greater attenuation of the iPhone 4, they got caught because the signal dropped so much it was visible even with the scammed bars.
It's like a fuel gauge that doesn't drop very much at first, and then drops quickly. You can use half your fuel and not see much difference, so you say, "Wow! Great gas mileage!" But when you get to the lower amounts, the gas usage becomes obvious.