The College Art Association has released a "Code of Best Practices in Fair Use" and it's been getting a lot of attention. You can read it here. We talked about this in class last week and the consensus was it's pretty useless. It says things like "artists should avoid uses of existing copyrighted material that do not generate new artistic meaning." And "the use of preexisting work ... should be justified by the artistic objective."
I don't see how that brings much clarity to the issue.