Tim O'Reilly has some very good points on copyright, piracy and digital distribution in an article on his website. Best quote: "Obscurity is a far greater risk to artists than piracy".
A mention of the article would be incomplete without a reference at the very same time to Creative Commons - which could be called CINGO - the Commons Is Not the GNU Organization. In other words it is an organization branding, and publishing a set of new open licenses with specific rights from public domain to right before an actual exclusive copyright.