Also, my Prius has a display used for showing fuel efficiency as well as the rear-view camera picture. Does that count?
I have an original MacBook Air, and absolutely love having a full-size notebook in such a lightweight package. I really value the full-sized screen and keyboard, and I bought a very small bag that's easy to carry along with me. Now when I'm out and about, I'm carrying a laptop *and* case that is smaller and lighter than most laptops out there. I even have room for a magazine or a book and a notepad.
That said, I actually don't see anything in these new models that will convince me to ditch my nearly-3-year-old MBA.
OTOH, I'm not sure this would actually work at all. When you print a halftone, you can actually overlap colors. You can physically print Cyan over the Black. But with e-ink, each pixel has to be a particular color. So you couldn't have a black screen if only half of your pixels have the option of displaying black. It would be gray at best.