I know many of my classmates have discussed plagiarism and copyright in their blogs but I'll throw in my two cents since we've spent quite a large amount of time in class on these issues. I agree that it's an extremely complex issue and the lines are very vague. Dr. Hylnka shared a story in class of one student being expelled from University for plagiarising, which I have mixed emotions over. One on hand, I completely understand the need to cite your sources and give credit where credit is due. On the other hand, perhaps this student simply had inadequate training as fair as citing his sources. When I was in my first year of University, I handed in a paper for Music History I in which I didn't cite anything, simply because I had never been taught in High School the conventions of proper citation. Thankfully my professor was extremely understanding and gave me a passing grade because I had a proper reference list. Now, perhaps if I had had a less understanding Professor, I too may have been expelled from University for a mistake I didn't know I was making.
This brings up the question of whose ideas are they anyway? I've always been much better at writing English papers because they are opinion based. I can't really steal anyone else's ideas because I am using one text, usually a novel, and my interpretation is coming from my brain alone. I simply need to be able to back up my opinion with proof from the text. I've always struggled with writing History papers though because I'm unsure as to what's common knowledge (such as date of birth, etc.), and what is someone else's ideas. And how did this person develop these ideas anyway? How can you discover something about a composer who's been dead for 300 years? It's all very blurry to me and I find that now I cite everything and very rarely use my own words in fear of plagiarising.
It's true that plagiarism in music is treated very differently. Composers borrow ideas from other pieces of music all the time. Generally, this is considered to be a tribute to that composer, not a stealing of ideas. And I suppose there's only so many notes you can use while writing a piece of music using the western system, whereas there are a plethora of words to choose from when using the English language.