MPO Files

MPO kitty! [1]
What are they
MPO Files are stereoscopic images, comprised of two overlapping 2D JPEG images. Each is used to represent the "left" and "right" view respectively, simulating a 3D effect. The 3D view of the Nintendo 3DS is created using MPO images. A device which does not support MPO cannot open and display the 3D image and may only display a JPG image version.
Some Digital Cameras can snap MPO Images, using two sensors spaced apart in the avarage distance of two human eyes.
How to make one
FAQ (that no one but the 3DWG asked) =
When the 3D effect is off, which one of the two overlapping JPGs is actually shown?