Of course this is a rumour, but it is Macrumors! I for one would be much happier with a metal back. The iPhone 4/4s is a thing of beauty, but I have to buy a case because I don't want to break the damn thing or scratch it etc!
http://www.t3.com/news/apple-iphone-5-to-rock-macbook-like-unibody-casing
http://www.t3.com/news/apple-iphone-5-to-rock-macbook-like-unibody-casing
In a note to investors, Brian J. White of Topeka Capital Markets reckons production will begin on a new 4-inch iPhone in June this year, following a recent visit to suppliers in Taiwan and China.
He says the sixth generation iPhone device will boast a look similar to the single sheet aluminum casings featured on recent iterations of the Apple MacBook Pro and MacBook Air lines.
White wrote: "In our view, this will be the most significant iPhone upgrade with a four-inch screen and a new, sleek look that we believe will require a Unibody case. This new, sleek look will be the most important reason that consumers decide to upgrade."