Sam Buss (University of California San Diego) and Michael Soltys (McMaster, CAS) solved an open problem in Computational Complexity: Is unshuffling a square NP-hard? This problem was originally posted on the Theory Stack Exchange (http://cstheory.blogoverflow.com/2011/08/happy-birthday-cstheory/). The resulting article has just appeared in the Journal of Computer and System Sciences (http://www.sciencedirect.com/science/article/pii/S002200001300189X").