I almost always swaddle Helen with her right arm free and her left arm tucked in. A few days ago, I noticed that she was doing an awful lot of waving. And it's always with her right arm. She's quite skilled at batting toys near her (right arm, that is), which brings her lots of delight - and allows me to get dinner started while she entertains herself. I guess if I want her to be a lefty pitcher in the future, I ought to swaddle her other arm.