Or, in Apple's official statement - which is only being passed out to news organisations which ask for a statement on the problem, rather than sent out (as happens with iPad or iPhone sales figures): "Gripping any phone will result in some attenuation of its antenna performance with certain places being worse than others depending on the placement of the antennas. This is a fact of life for every wireless phone. If you ever experience this on your Phone 4, avoid gripping it in the lower left corner in a way that covers both sides of the black strip in the metal band, or simply use one of many available cases."
The problem emerged within hours of the first iPhone 4 devices being delivered to customers in the US, with dozens posting videos to YouTube showing mobile reception dropping off dramatically when they picked up the phone. Some users wondered why Apple had not spotted the problem during its testing of the iPhone 4 before its launch, and wondered whether the £25 "bumpers" that Apple sells to go around the casing - and protect the metal antennas - was an implicit acknowledgement of the problem. Apple had no comment on Friday on whether it had discovered the problem during testing, or only after the phone went on sale.
http://www.guardian.co.uk/technology/blog/2010/jun/25/iphone-reception-problems-solved