Apple announced the new iPhone 3G S on Monday with identical look as that of iPhone 3G. So, after this announcement, the first thing that came to my mind was the leaked images of new iPhone matte case, proved to be fake. Strangely enough, however, the photos do appear to have been real cases for the iPhone 3G S as per MacRumors report.
The leaked matte case design was clearly marked with a new model number A1303 and FCC ID BCGA1303A. Based on the official records released yesterday, this FCC ID does correlate to the new iPhone 3G S:
Since these model numbers and FCC IDs did not follow an obvious progression at the time its pretty unlikely that someone just guessed the right ID. Perhaps at the last minute Apple decided against a design change, but the original leaked case was clearly produced by Apple.