As far as literature is concerned, I would posit that there should be one price for a digital copy of a book and a slightly higher price for a printed one to compensate for the cost of printing and publishing.  With either purchase, one should get access to a digital copy as well as an audio copy so it can be enjoyed anytime, anywhere, anyhow.  And the industry should price accordingly to ensure there is aporopriate margin for all involved.

At the end of the day, the IP is the IP.  What form it gets consumed in is irrelevant.  This approach will likely increase the overall sale of books as it will make it easier for people to actually read them.

Agreed. Actually, I’d be overjoyed with a future where I buy the “platonic goods” (the rights to own/enjoy copies of a given work) and then pay an additional fee each time I request a copy in some desired format. (Say, $3 to offset the cost of printing, $0.10 for the cost of wireless-transmission, etc). I’d be OK repaying the cost of transmission/manufacturing should I lose my ‘copy’. That would be the ultimate.