Originally Posted by FJames
A quick calculation of 1024 x 768 into a 6" diagonal says 213 dpi. The links ijdod posted above would appear to indicate that they are both using the same eInk brand display, which would make sense in spite of the small difference in the published specs (eink.com site currently not responding, so I can't check).
They're all using a flat light pipe layer over the eInk display, like the Nook. The Nook has shown that the slightest damage to that layer is very visible when the glow light is turned on, so you would certainly want it to be well protected by another hard layer on top of it.
The Kindle and the Kobo are lighting the screens differently then B&N. It's not a layer like the nook.