Interestingly enough, I finally got my iPhone 4 yesterday, and when I was at the Apple store, I was looking at the bumpers and thinking, "it's too bad I'm not here tomorrow, because I'll bet I can get one of these for free tomorrow." Well, I was wrong. I'll have to sign up for them to send me my free bumper next week. I could have bought one yesterday and received a refund, however.
In Jobs' defense, some iPhone 4s do in fact seem to perform worse than others. My wife's phone dropps calls much more frequently than her iPhone 3G did. Mine seems to be an improvement over the iPhone 3GS. I have made a point of paying attention to not bridging the two antennas with my finger, however. Maybe they'll develop some kind of diagnostic and offer a replacement for the worse phones without having to do a full recall.
After a week of playing with my wife's iPhone 4 and a day of mine, I can say that I won't be taking Steve up on his offer to let me return my phone. Antenna problems or not, I'll have to say I agree with Consumer Reports: The iPhone 4 definitely has problems with reception, but I still think it's the best smartphone on the market. And the bumper really does seem to solve the problem in real-world conditions, which is why I was sure that Apple would try to solve the problem by giving away bumpers.