The Path of the Muses
This article is a thorough treatment of the ideas George Lucas borrowed from Frank Herbert's Dune series and adapted for Star Wars. I don't believe the intention of the article is to accuse Lucas of plagiarism (though others have all but accused him of such). Indeed, as the article goes on to mention Herbert's diverse influences for Dune, I think the author's intention is to trace a lineage of inspiration from one artist to another (Lucas was inspired by Herbert, who was inspired by Shakespeare, who was inspired by Sophocles). This "Path of the Muses" is integral to artistic creation, and I would be remiss if I didn't mention that contemporary intellectual property law threatens this progression. (For an amusing take, read this.) But that is a discussion for another time.
On a related note (admittedly engaging in some semantic gymnastics), I will be seeing Muse, the band in concert this Sunday. Can't wait!