We've seen accessory makers spill the beans on upcoming products before. In the Treo space, an accessory maker went so far as to put their demo unit on a convention show floor. There was also the "fatty nano" rumor that seems ludicrous right up until the moment that Apple released precisely what the accessory maker had leaked. Things on the iPhone side are, of course, quite a bit more hush-hush, so apparently what these accessory makers have is just some rough dimensions, according to iLounge:
Companies overseas have already started working on products for this one, which is basically the same size as the current iPhone, but has slightly different curves, coloration, and materials.
We also get confirmation of the tip-top "Black and basically the same" rumor. The glossy black plastic is apparently quite a bit fancier than what you're imagining, and toss in a very slight taper across the back as well. A few slight adjustments to the location of the various sensors on the iPhone and the story looks pretty complete and pretty legit.
Oh, yeah, looks like color options besides black might be thrown into this heady mix of iPhone 3G stew as well. MMmmmmm ....HSDPA.