A comment at The Volokh Conspiracy, pointed me to “Infringement Nation,” a paper discussing the gap between copyright law and our social norms. The part you should go read is IV.A. “Infringement Nation,” which starts on page 8. Due to extensive footnotes, the 1000 words are spread across six pages.
The shorter version is that common activities are technically illegal, and the only things stopping billion of dollars of lawsuits (per person, per year) are good will and the difficulty of enforcement. If you include the text of an e-mail in a reply, that is an illegal reproduction of someone’s original work. If your game or music volume is too loud, that could be an illegal public performance of a copyrighted work.
On one hand, hey, can we track down those jerks who copy others’ blogs to generate faux content around a bunch of ads? Every single post on there is a potential $150,000 offense. How about those jerks who play their car radios loudly enough to rattle your windows? Illegal public performance, clear infringement.
On another hand, how many gaming blogs are posting their sixth screenshots? Did you contact the publisher for permission to reproduce artwork from their game? You are also making a derivative work, and your chat box may show infringement of other players’ copyright in their (short) textual creations. You are also distributing said illegal works, and engaging in contributory infringement by linking to other infringing blogs. Given the web of sites participating, there may be grounds for conspiracy or racketeering charges. That the developers want your free publicity right now does not mean that they have granted you legal permission to violate their copyrights.
Many people take the high ground on not stealing music or engaging in file sharing. Have you considered how you might be “a little pregnant” on violating copyright law?
If you read this post aloud, you created an unapproved derivative work. If someone else was around, you also conducted a public exhibition. Where is my royalties check?