A new study by the
Royal Institute of Technology in Stockholm, "Screening environmental life cycle assessment of printed, Web-based, and tablet e-paper newspapers," examines the environmental impact of e-paper versus the process of creating paper-based newsprint, and proclaims that reading e-paper for 30 minutes equals the environmental impact of producing paper for a 30 minute read. It also suggested that reading the same content on the web would have the same environmental impact after only 10 minutes.
The study took into account the full process of preparing paper for reading, including harvesting, processing (which includes significant chemicals and electricity), transportation, and of course, disposal, and compared that to the process of manufacturing an e-paper reader (which can be reused... length of life also figured into the equations).
(Report in PDF, English:
http://www.csc.kth.se/sustain/publications/reports/)