Joel.net's copyright notice has an interesting link on copyright definitions. It's nice to know that some people still understand the meaning of intellectual property.
Today, I read an article on an ASP.NET site (links withheld to protect the guilty) where the author quoted the MSDN documentation verbatim in at least 3 separate places. However, not a single reference was made to the MSDN documentation. Just because it is easily accessible does not make it your own work: give credit where credit is due.