The New York Times has an interesting article laying out some of the issues surrounding intellectual property and the public domain. Many quotes from the “CopyLeft” crowd (Lessig, Zittrain, and Fisher) and a few from the other side of the argument as well.
“The Tyranny of Copyright”

Ed Lazowska adds: Among my friends and collaborators who build and distribute research software, essentially all have adopted some variation of the BSD model rather than the GNU model. The need to incorporate software from disparate sources makes the GNU model too restrictive, IMHO.