ZDB has been working on a new type of LCD based screen tech for some years now, and they've primarily focused on signage, both for retail and for offices. The Zenithal Bistable Display (ZBD) has at least one important detail in common with an E-ink screen. Both are bistable, which means that they don't need power to continue to display an image. But other than that the underlying tech is completely different.
ZBD has a number of different labels sizes, but all are built around the same system. I have a picture of the labels below, and behind each label is a small battery, a controller chip, and a small radio receiver. One of the really cool features of this system, and the reason why it's expected to save money, is that all the labels in a store can be controlled remotely. A single base station, usually mounted in the office, can update each of the labels remotely.
Battery life for the labels is around 5 years, but there hasn't been enough time for that to actually be tested. These labels are in use in over 100 stores around the world, including the Italian supermarket chain SISA. But no one has had it quite that long.
I've seen similar systems on display at various tech shows, including ones from BridgeStone/Delta and E-ink (completely different use), but this is the first that I've heard of in use in a retail location.