Now all that said, from all I've heard the authors of the GPL were quite competent in what they were doing, so it is quite likely that the GPL says what they meant.
I think the most important thing is about remedies, and there is quite strong precedence. It seems that if you use open-sourced software and don't do what you are supposed to do according to the license, you are a copyright infringer, and not someone in breach of contract. So the damages are those of a copyright infringer (up to $150,000 per work, or the proven damage), and not those of a person in breach of contract.