You're going to hear a lot more about this - hopefully everywhere you turn.
All I can say is that it sure bums me out to catch wind of one of my patterns posted on one of those sharing sites. My artwork is really crappy when I'm bummed. You don't want crappy designs, do you?
Here is a new website that has sprung up specifically to champion this issue: http://needleworkcopyright.blogspot.com/