As much as I love Apple's products, I have to say this announcement marks the biggest piece of BS reversal/cover-up I've seen in my lifetime. It's as if the sideways universe never existed at all (see Lost).
Now before you dismiss me as a hater or whiner, let me just say I'm perfectly fine with my iPhone 4 and have no intention of returning it. I can reproduce the issue (already detailed in other posts) but am not affected in general use, either with or without a case.
However, as an RF Engineer with a PhD in EE, I can guarantee this is not a software issue and I find the audacity of such a cover up to be rather incredible, yet ultimately I can see how it happened. The antenna engineers took a risk with this design, and I'm sure someone knew something like this could happen; either that or their antenna staff is a bunch of idiots and that's why they are now hiring new engineers. The brilliance of using this *software* coverup is that it's hard to debate. There are no signal strength standards attached to bars, so the Apple software folks can simply tweak to their hearts delight to make the signal attenutation no longer appear under different signal strength conditions. Voila, the problem has vanished.
Problem for them is when people continue to run tests with Speedtest and other means of testing such as dropped calls. The latter is probably unreliable and difficult to legally prove as it could always be blamed on the opposing party. Speedtest is probably the best way to confirm you are still losing signal strength, but even that is subject to issues that would be hard to prove in court.
Pretty genius legal move on their part to cover their asses and placate some of the masses, but it stinks if you ask me.