MacRumors just reported that a tech blog in Japan has posted a mockup design of the upcoming iPhone 5. The supposed mock-up shows an iPhone with an aluminum casing, which will be more durable than the current glass casing and will help prevent damages to the iPhone 5's frame.
The antenna is also said to have gotten a redesign, and the site reported that Apple has decided to incorporate a logo antenna, saying the "antenna will be designed to penetrate cellular and Wi-Fi waves via resin made Apple logo placed case back, design of iPhone 4 using side exposed steel antennas seems to be abandoned." It is reported that the logo will be made of a resin material which will host the handset’s Wi-Fi, cellular and all other radio antennas.