The United States Virtual Astronomical Observatory program is the operational facility successor to the National Virtual Observatory development project. The primary goal of the US VAO is to build on the standards, protocols, and associated infrastructure developed by NVO and the International Virtual Observatory Alliance partners and to bring to fruition a suite of applications and web-based tools that greatly enhance the research productivity of professional astronomers. To this end, and guided by the advice of our Science Council (advisory committee), we are focusing on five science initiatives in the first two years of VAO operations: (1) scalable cross-comparisons between astronomical source catalogs, (2) dynamic spectral energy distribution construction, visualization, and model fitting, (3) integration and periodogram analysis of time series data from the Harvard Time Series Center and NASA Star and Exoplanet Database, (4) integration of VO data discovery and access tools into the IR AF data analysis environment, and (5) a web-based portal to VO data discovery, access, and display tools. We are also developing tools for data linking and semantic discovery, and have a plan for providing data mining and advanced statistical analysis resources for VAO users. Initial versions of these applications and web-based services are being released over the course of the summer and fall of 2011, with further updates and enhancements planned for throughout 2012 and beyond.