The Inspire (AT&T) has an aluminum shell with a rubberized battery door and cowl around the camera. The dummy Bolts have an entire back panel made of the rubberized stuff and there's no metal to be found on the outside. I wouldn't usually judge from a dummy unit, but the Inspire dummy unit has the same aluminum shell as the production model.
I don't know what Bob From Wirefly and the dude above were talking about when he said the Bolt had a metal frame. It could be something that was dropped after the test units were shipped. Or he could be talking about a purely internal frame. Either way, I won't feel guilty about putting it in a case.
Also, any idea what the plastic nipple (navel) is on the back? Just below the kickstand, right in the middle.