For me, the biggest issue is the ability to buy a 'Secure' Mobipocket ebook, which I can then read on *ANY* of my e-ink devices. Clearly, Bookeen's Boo Reader (on the Cybook Gen3) generates a valid, registerable, PID. What I'm hoping for is the (eventual) ability to place OpenInkpot and FBReader onto a device, have it (FBReader) generate a PID for that device which I can add to my list of registered devices, and read my Mobipocket (or Fictionwise) mobi purchases - without having to do something illegal such as run MobiDeDRM against it.
I also want to be able to apply the same formatting on all ebooks and have the same look-and-feel on all such platforms. I've seen what some ebook publishers call 'mobi' and their formatting sucks. Others do a much better job. I won't name names.
Derek