The technique the driver uses to prevent printing is a feature of the PDF format and is really Digital Rights Management (DRM).

FORBES: Green Tech? Only 'Cause it's Not Ripe

They also point out that new technologies such as print on demand, which makes printing short runs of physical books more economical, should help them squeeze more money out of the old-fashioned format.

ECONOMIST: The future of publishing: E-publish or perish | The