DRM a non-solution says Jon Udell:
When I worked with O'Reilly on its electronic reference library, Safari, protecting the IP was a top concern. We implemented such controls as are possible in a web-based medium, including spider detection and digital watermarking. But I'm sure I lost more sleep over these issues than Tim O'Reilly did. His experience tells him to trust his customers to do the right thing: pay O'Reilly a fair price for its content, and publicly uphold that social norm. By and large, they do. When O'Reilly content shows up in unauthorized form on the web, it's often customers who first spot it and report it.