Taiwanese site Apple.pro republishes some photographs originally posted to Weibo, a Chinese microblogging service similar to Twitter.
The images claim to be of an "iPhone 4GS" test model running iOS 4.0. The unit appears to be identical to the iPhone 4 with a reported 5 megapixel camera based on the diagnostic software. The iTunes artwork looks different but as some readers have pointed out -- no camera and looks to simply be the original iPod Touch artwork.
Beyond that information, there is little else that seems remarkable about the device, and due to the difficulties in translation, we can't even be sure of all the claims, nor the creditability of the original source. As such, we are posting for discussion and interest alone, and not necessarily that these represent accurate images.
The next iPhone is expected to be released this september and there have been reports that the new device might be undergoing testing within the current iPhone 4 casing. The Wall Street Journal has claimed that the final design will be "thinner and lighter" than the iPhone 4.
Update: Based on serial number and iOS version, it seems this is most likely an earlier iPhone 4 prototype. The serial number indicates that the phone was manufactured in the 48th week of 2009.