The internet continues to shake up the world of copyright law. Most people don't know exactly what copyright infringement entails, and it's constantly getting them into BIG trouble.
One of the more popular cases over the years that ended up favorably was Lenz versus Universal Music Corp. In 2007, a very proud mother posted a video of her daughter lip syncing to a Prince song, then posted it on Youtube for all the world to enjoy. Universal Music Corp was not amused and forced Youtube to take the video down because they felt the mother's video violated their copyright of the song.