We received this crystal clear image of what a source claims to be the iPhone 4 for Verizon. Update: It's an alternative cover.
Update: Actually, it's not the Verizon iPhone, but an alternative back cover. But now that I've seen it this way, I know I want it.
In addition to that, there have been credible reports on Apple engineers being aware of back glass problems that make the iPhone 4 design too fragile. An aluminium back makes sense, and this retro brushed styling looks like something that Jon Ive would do.
However, it could also be a clever, very well done fake. Not a Photoshop, but a custom-made aluminium back. The markings could have been made with a laser. It does look amazingly good, however.
Our tipster claims that the Verizon iPhone has a "brushed aluminium back and a standard black front." He says that they will come packaged with a bumper. He also points out that there will be a product(RED) version of this phone.
Again, this source is completely unverified at this point, so no matter how good it looks, take this with a full spoon of salt.