In many interviews with many bands and artist I have heard the best form of flattery used. Many bands and artist over the years and yerars of music have rercorded others music with your own twist in thier own way or not. The blues is a very good example and Zepplin is a good example of that as well many of thier songs are based on old blues tune form long since dead guys. And seriously many of us have no idea what goes on behind the scenes of the liscensing and production of these recorded songs if it was really a problem there would be more law suites between artist than law suites betwen artists and Kazaa, Limewire, Napster, ect.