I reported above that my iPhone 4 purchased from Orange in France works just fine no matter how I hold it. Since that post I have traveled to Slovenia, the Netherlands & Belgium and have had zero problems with reception.

So either the batch sold in France doesn't have the supposed defect, or the networks in Europe are much better than AT&T's in the USA. Based on my not-so-scientific investigations.

Note: I will report I have had to reboot my phone 3 times since buying it a few weeks ago. But I blame that on IOS 4.0 which seems a bit buggy.