In the eighteen months since it came down, the U.S. Supreme Court's decision in AT&T Mobility LLC v. Concepcion has variously been described as a "watershed," a "game-changer," and perhaps even "[t]he most significant" case of the Court's 2010 Term. I share this assessment, but not for the familiar reasons. In my view, Concepcion is significant not so much because of what it portends for the future of aggregate litigation or the ability of small-dollar plaintiffs to redress systematic wrongdoing by large-scale defendants, but because it signals something of a paradigm shift in the law of Federal Arbitration Act (FAA) preemption.