Also check out 18F [1], which focuses on pushing forward how tech and the government work together. They run a 12-month Presidential Innovation Fellows program [2] which works more intensely on innovating with specific groups within the federal government. USDS is more focused on modernizing and ensuring some basic technical functionality of a lot of the core aspects of the government (which is incredibly important and impactful, but is less about innovation -- see a comparison here [3]).
[2] https://www.whitehouse.gov/innovationfellows
[3] http://ben.balter.com/2015/04/22/the-difference-between-18f-...