This defies common sense though as neither the makers of those devices nor the carriers are having a flood of calls complaining about dropped calls due to the way you hold the device and no one is thinking about offering $30 bumpers to solve any problem.
Smelling something fishy, PC Magazine has rounded up many of these phones and run their own tests. They pretty much ignore the bars though as those aren't the best indicator of signal strength. Instead, they relied on the "signal receive strength in -dBm" which is a more accurate indicator of the phone ability to connect.
To make it more interesting, PC Magazine gripped the phones with both hands covering the entire surface of the phone except for the screen. While all of the phones show signal degradation when gripped in this wholly unnatural way, none had the propensity to drop a call like the iPhone 4 did when it is gripped like a phone should be gripped.
Why is Apple bothering with this? They have already owned up to the issue, so they should just fix the problem. Stunts like this only server to make them look childish, and provide fodder for the blogosphere.