In that last project a hacker found a way to connect a Kindle to a Raspberry Pi over USB and turn the Kindle into a USB monitor, but now we can do one better. Hackaday has found the Pi-nk, a new project which turns a Kindle into wireless monitor.
This is by no means the first project with a wireless monitor; you can in fact turn just about any Android tablet or the iPad into a wireless monitor, but this idea is still unusual for E-ink devices.
And if you have a Raspberry Pi 2, this is an idea which you can replicate. The developer has put together a detailed how-to which explains how Pi-nk uses wireless instead of USB for almost all of the connections (including the keyboard). He worked from a Kindle Paperwhite, but since all Kindles now ship with Wifi this project should work with just about any Kindle model (just so long as it has been hacked).
Based on what I am reading, I don't know that this will work with other E-ink devices, and that's a shame.
I would really like to see this hack applied to the Sony Digital Paper DPT-S1, a writing tablet with a 13.3" E-ink screen and an $800 price tag. That much larger screen would be a whole heck of a lot more useful than the 6" screen on the Kindle, but the DPT-S1 doesn't
even have a web browser, much less have an active hacking community.