Well, check this out: a law went into effect in Sweden yesterday allowing rightsholders of copyrighted material to go to court to make public the names of Internet users based on their IP addresses. The result? Ars Technica has the money quote:
The EU's Intellectual Property Rights Enforcement Directive (IPRED) requires all member states to adopt tougher protections against piracy and counterfeiting. Sweden's own implementation of the law went into effect on the first day of April and had an immediate effect; Internet traffic passing though the country's main exchange points fell nearly in half.
This is an issue that must, must, must be covered in your acceptable use policy. Especially in 1:1 environments. It will be interesting to see how this all goes down. Maybe it'll stop people from clogging up the Internet so I can spend more quality time playing online games. Ha!