Fair Use

So I'm posting this here because the maze of information on the web can be dizzying at times..

Does anyone know what the story is on using screen-shots for art purposes, and the copyright infringement vs. fair use issue? Maybe it falls under satire or criticism, but I was hoping maybe someone had some personal experience (positive or negative) with the issue? I would like to consider the images of the web as my day-to-day landscape waiting to be photographed, but likely not everyone will see it like that.