I remember being very impressed by the Iridigm “butterfly wing” display technology at least as far back as 2004, before they were acquired by Qualcomm. The basic idea as described by Scientific American is to use the same principle as a butterfly’s wing to create color via interference rather than pigment (as in paper) or emission (as in most computer displays). Advantages include a truly paper-like level of ambient-light reflection, and zero power consumption except when changing the display. These are both highly valuable properties for an e-book reader, which is why it’s exciting that Qualcomm intends to come out with one.