E-ink has a factory in MA where they make make the source material for their screen. It comes off the assembly line as a single plastic sheet that measures several feet wide and up to a mile long. The sheet is then rolled into a cylinder (much like paper products) and shipped to Asia.
The factories in Asia unroll the plastic sheeting, cut out the standard screen sizes (5", 6", 9.7"), and then mount this material on backplanes.
The sheeting at right is the same material as the screen that you can see on your Kindle. But what you cannot see on your Kindle is the backplane, and the backplane is actually what makes the screen turn from black to white and so on.
You can think of a backplane as a glass plate of tiny magnetic switches. They're laid out in a grid (much like pixels on a screen). When a switch changes from positive to negative, it changes what you can see on the screen by attracting one color and repelling the other. The color you see is the one that is being repelled by the backplane. It's more complicated than that, and I didn't really explain how the grayscale works, but it's an adequate mental image for now.
I'm sure you know that the iriver Story HD has a higher resolution E-ink screen than on any other ereader. The screen has a higher resolution not because it came from a better sheet of plastic but because of the backplane. The Story HD uses a backplane that can squeeze in more pixels than can be found on the Kindle.
You might also know that the 5" E-ink screen has the same resolution as the 6" screen (600x800). Again, that's not becuase of the screen material, but is a result of a backplane that can pack the pixels in tighter.
Did you click on the pictures? Pretty cool, huh?