This is an interesting campaign. A PDF that cannot be printed, a WWF!
It is a green idea, and a gateway idea. By gateway I mean that it immediately brings to mind many options. One is the idea of having by default computers that cannot communicate with printers but one can pay for a plugin that makes the connection.
Not sure how far the WWF PDF will spread and how successful it will be. People can take just simple steps like taking a screenshot of the file and then print it. Successful or not, I think the next idea built on this one will go far.