Remember these iPhone 4G prototype pictures that surfaced last night? Well, “multiple sources familiar with the next iPhone have confirmed to me [Daring Fireball’s John Gruber] that the back is made out of some sort of fancy glass — and looks pretty much exactly what’s pictured at Engadget.”

This annotated image shows break points in the casing that suggests the side compartment might be removable to allow the user to replace the battery.

[via Macrumors]