With a kindle, how do you keep multiple pages in front of you at the same time?
That's not to mention e-books as sources. Even if we figure out the virtual library issues (lest we bankrupt every grad student -- comprehensives in the social sciences can encompass 200 books!) we still have to look at workflow. Should the grad student have 4 kindles all synced, every e-book markable with programmable gestures both robust and simple enough to compete with paper?
Of course, printing every little e-mail is nonsense; but I'd rather correct my thesis on paper than on screen, for instance.