Information about federal spending can affect national priorities and government processes, having impacts on society that few other data sources can rival. However, building effective open government and transparency mechanisms holds a host of technical, conceptual, and organizational challenges. To help guide development and deployment of future federal spending transparency systems, this paper explores the effectiveness of accountability measures deployed for the American Recovery and Reinvestment Act of 2009 ("Recovery Act" or "ARRA"). The Recovery Act provides an excellent case study to better understand the general requirements for designing and deploying "Open Government" systems. In this document, we show specific examples of how problems in data quality, service design, and systems architecture limit the effectiveness of ARRA's promised transparency. We also highlight organizational and incentive issues that impede transparency, and point to design processes as well as general architectural principles needed to better realize the goals advanced by open government advocates.