Information about the forthcoming second-gen, 3G-capable version of the iPhone has evolved from vague rumors and speculation to pretty specific details. Engadget has the scoop, and says it has learned from a "trusted source" that the 3G iPhone will have a built-in GPS and a slightly altered physical design.
The device will reportedly trade its predecessor's scuffed metal backplate for a glossy black finish (check out Engadget's post for a picture). The size and shape will stay more or less the same, but the new iPhone will be a little thicker, and its edges will be more rounded. Incidentally, the headphone jack will be flush with the body, the volume buttons will be chrome, and the battery still won't be removable.
According to Engadget, the 3G iPhone may show up as early as July. Of course, the site points out that Apple could change its plans at any time.