On Macrumors forum, several iPhone 3G owners report cracked back cases:
All photos features a White iPhone 3G model, but it might well be because it is easier to spot the defect than on a Black model. If you look carefully it looks like the plastic case broke under pressure along a more solid compartment located inside the device. This is typically something that can happen when carrying its iPhone in a pocket, especially in the back pocket of trousers. However, considering the number of reports, one can conclude that the case seems to be relatively fragile. So be careful.
Les nombreuses photos sont toutes faites sur des appareils blancs, les craquelures étant
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