The WhiteHouse has recently published the U.S. Digital Services Playbook: http://playbook.cio.gov/
Which outlines ‘plays’ that revolve around agile methodologies. Many stating directly: use agile!
They also have the TechFAR handbook which dives into more technical approaches that revolve around agile and some of the technical excellence methodologies: http://playbook.cio.gov/techfar/
Check these resources out!