The veracity of the images remains doubtful. They appeared on a forum at iPhone5Parts.net and later on NoWhereElse.fr, which has previously been the source of iDevice-related rumors.
The photos purportedly show close-up detail of the rear housing of a new iPhone, dubbed the iPhone 5S. Since Apple has gone the "S" route before (iPhone 3GS, iPhone 4S) and iPhone 5S is possible, but this early in the game, it's hard to believe a leak has already occurred.
The site indicates that the iPhone 5S' release date will be next summer, which would pull in the annual refresh of the device by at least a few months, and might seriously tick off iPhone 5 owners. Apple hasn't pulled in the release of a device like that, with the exception of the iPad 4. iPad 3 owners weren't too happy about that release.
The post says:
From the background, it seems that the pictures were taken at the assembly line of an operation stage. The photographer has showed the front and rear side of the housing, which looks very similar to the iPhone 5. However, the reason why we say it is a suspected iPhone 5s rear housing is that the specific information below the logo, which are replaced by 'X.' Usually, the parts with 'X' stand for test prototype.Those countries that haven't even received the iPhone 5 yet must be green with envy: no iPhone 5 for them and yet here we are with the first rumors.
Naturally, this rumor must be taken with a grain of salt, but those who recall the accuracy of the iPhone 5 rumors might be wondering about the validity of these pictures.
A slideshow of images can be seen here.