• Perlmonks, or any other place full of young geeks is not at all the right place to inquire about legal questions. You should consult a lawyer.
• The copyright law is very clear. If you write it, you have the copyright. No notice required. And if it isn't absolutely clear the author put something in the public domain, you may not assume it is. The copyright law is the same in most countries (commonly known as the Berne convention). The US was one of the last countries to sign, back in 1989 IIRC.
• What isn't very clear is the role of links or "frame hijacking". Hyperlinks didn't exist when the Berne convention was made, and there haven't been many law cases made yet. We can all call the people linking and copying your site bad names, but that doesn't help you. If you want to do something about it, get a lawyer.

  I know of one case (in the Netherlands), where the Dutch Railway sued a student who had "frame hijacked" one of their services. The student lost - on the bases that despite he wasn't technically copying the material, his site strongly suggested he was.

• Note that nitpicking about technical details of when material is copied and when it isn't, is (luckely!) not going to work for the internet. Otherwise newsgroups, email, proxies and sites like perlmonks would all be in violation of the copyright law, as they all copy material without explicite consent of the copyright holder.

Abigail