It's been said before. Everyone should have picked this up in school. Maybe in the past, before the Internet, you might be tempted to copy a paragraph or a sentence here and there. No more. The Internet is forever, and everything you write is there forever. And it's almost instantly search able.
Don't believe me? Read "How my blog started the avalanche that buried presidential aide Tim Goeglein" by Nancy Nall Derringer in Slate today. Here is the link: http://www.slate.com/id/2185657/
I wonder how many people are going to fired ten, twenty years from now for plagiarizing other people's content (...and all the snotty, mean, vicious things they write on their own blogs or while commenting on other people's...). Seriously people, do not copy other people's stuff.