From AnandTech’s research. Here are the major points:

• Reception in average conditions is sometimes significantly better on the iPhone 4 than on the 3GS
• Signal strength is sometimes the same as or worse than the iPhone 3GS
• The iPhone 4 is better at holding onto calls and data at very low signal levels

In other words:

Apple opted for good performance in low signal situations (and style of course) over maintaining consistently better or unchanged radio performance compared to the 3GS.

The reality is that for the majority of people. The iPhone 4 performs better in most situations that the iPhone 3GS does. Also most people use the iPhone 4 with a case. That means that very few ever see the so called grip of death situations.

I do not expect Apple to do any sort of ridiculous recall today. The most I see is an Apple store gift card for a free case and a call for anyone who is unhappy to return the phone with no restocking fee.