I read about Kottke getting nasty legal threats from Sony and liked this post here. Having worked at a company that was sued, and PAID OUT over $250 Million dollars to content companies, I am painfully aware of the use of copyrighted material. It would behoove those of us who want to comment and hold stuff out there for others to get acquainted with the copyright laws. If we don't like the ways that the laws are being written, and enforced, we need to do something about it by calling our legislators and creating alternative models that don't step on the laws and invite trouble.
Aside from any issues of newsworthiness etc., the content companies are clearly within their rights to take the actions that they do, and it is a rational approach given existing law. I think the comments that Lawrence Lessig makes regarding the need to change these laws should become important reading material for people who don't like the state of the law.