Not months later. YEARS later. They float a concept car, pick up the reaction, go back to the drawing table and then after a minimum of 2 years they unveil the end result, e.g. the cool concept car with all the cool parts removed by a nervous committee.
Typically those cars are dummy mockups that can't even be driven.
This phone, however, is about to be released in 8 weeks, and Steve will probably want to say "available today" at the Keynote. The specimen found is fully functional. But the most important clue is the fact that this picture (and others like it) have emerged from China:
That design is identical to the Gizmodo phone.
Now, the iPhone equivalent of a concept car would not have been manufactured in China, it would've been hand made in Cupertino. Why would Apple A) go through the trouble of having prototypes manufactured in China, and B) trust such a prototype to the Chinese when history shows that they leak like crazy?
The prototype stage is looooooooong gone. Mass production should be starting up as we speak -- the manufacturing date of any freshly launched Apple gadget is typically a few weeks before the launch date, and all the depots around the world need to stock up well ahead of the launch date.
Yes, the Gizmodo phone is not FINAL final, or else it wouldn't have placeholder text on the back, but it is *not* some early prototype or test bed.