Annotations allow users to apply a layer over the web. The question that needs to be asked is whether this is a good thing. Mike Caulfield adds his perspective:
it's your browser, and you're allowed to annotate anything you want with it. But the separate question is what should be encouraged by the design of our technology. People want to turn this into a legal debate, but it's not. It's a tools debate, and the main product of a builder of social tools is not the tool itself but the culture that it creates. So what sort of society do you want to create?
And this ...
Annotation is incredibly promising. It's also a chance to get this sort of social design right, and learn from the repeated mistakes of the past. I'm hoping those involved with it right now will reach out to those with a deep and personal knowledge of how these things go wrong and get ahead of the curve for once. (Source)