Where'd that term come from? The screen's white, isn't it?

*rolls eyes*

pffft

Nevermind...

http://en.wikipedia.org/wiki/Silver_screen

A silver screen, more correctly called a silver lenticular screen, is a type of projection screen that was popular in the early years of the motion picture industry.

The term silver screen originated in reference to the actual silver content embedded in the material that made up the screen's highly reflective surface. While actual silver screens are no longer commonly used, the term silver screen has passed into popular use as a way of referring to refer to projection screens in general and motion picture projection screens in particular.