"Squad Traits" is pretty much what you expect. It is a list of traits that affect the players as a whole instead of as individuals. What I was most impressed with was the versatility these traits can bring to the game.
The author recommends several ways they can be used, including increasing difficulty, unifying characters thematicly, and even as temporary mechanics to go along with a mission's plot.
After reading this I am starting to think of traits in different ways!