Are the new plastic backs on the 3G iPhones cracking?
There seems to be some reports of the back of the new iPhones cracking.
I have had my iPhone for only a week (black) and I don’t see any problems yet but there are discussion about it at the Apple forums and on various web sites. MacRumors & Engadget Mobile.
As of now, it seems to only be effecting the White iPhone.
Is your iPhone cracking???
aGEEKspot 
I also have the black model and have not experienced any problems with the back casing cracking. I read on the mac forums that this problem also extends to the rounded edges on some macbooks. I would be interested in knowing what kind of case the ones who are experiencing this problem are using.
I am surprised that Apple would continue to build their products out of plastic when aluminum has worked so well and has not had the “cracking” problem. Who knows, it might boil down to cost $.