Actually I really don't see why PIM apps cannot become part of this? 8)
PIM apps normally display pretty static data via static pages/dialogs/windows. eInk would make it a joy to use PIM apps, since battery life is wonderful! 8)
Just don't display a running clock and everything should be fine.
Some means to do simple notes taking would be excellent, making the PIM app complete. ok ok, this becomes more like a PDA ... but hey, while we are at it ...
Besides, I think PIM + eReader is a better match than PIM + PMP!
Current PDAs is more PIM + PMP which to me is not a very good match of features.