On Tuesday, Google's John Mueller had a video hangout just on the topic of duplicate content. Duplicate content is one of the most popular topics in the SEO space. Google has said time and time again, there is no such thing as a "duplicate content penalty," but it is clear that having duplicate content can cause ranking issues - even without a penalty.
John Mueller spent over an hour on the topic, about 19 minutes of presentation time and over 40 minutes of question and answer time. Here is the video, which is a nice video to listen to while you work:
Here is the Google+ page where you can see some of the questions.
I don't think anything is particularly new in this hangout but it is still good to listen to.
Forum discussion at Google+.