The Open Book Project
I really like the Idea.Since I bought a reasonably open Kobo recently, I feel the main pain point with eRaeders though is actually getting something to read on them. A dozen stores with DRM exist and the few sites without DRM naturally have limited selection.
Also reading pdfs is really not great, yet converting them seems also unreasonably hard.
So the problems seems not to be the hardware only, but the whole stack from hardware over software to content.Still, an open eink device could be fun and can certainly be used for more than just reading books.