Had my iPhone Duo for about six hours and had probably opened it fewer than 20 times.
I was showing it to a friend, and as I opened it, I felt something around the internal hinge, underneath the screen.
As I continued opening it, I heard an audible crack, and the screen broke right along the hinge.
There were no marks or damage on the inner screen’s surface or the external hinge to suggest anything had been caught or damaged.