According to a translated Chinese source (I know, a little sketchy to say the least) the iPhone 5 will revert to an aluminum back panel, in place of the latest generation's entire glass affair. The picture above is a concept however we would expect Apple to also provide a flash for the camera!
The source claims that Apple will dump the glass panel due to problems with scratching, breaking and the weight of the panel. The iPhone 5 is claimed to more resemble the latest iPod touch design. The original iPhone also had an aluminum rear panel and many still believe this model had the best build quality.