1) A machine-learning competition to overcome scarcity in the radio frequency which is INSANELY fascinating and, if they pull it off, hugely impactful -> https://spectrumcollaborationchallenge.com
2) A program to build technology to drive “swarm sprint” exercises to inform tactics and technologies for large groups of unmanned air and ground robots in urban environments. Yes, like how do we build a collaborative air drone army.
And PS they are having a hacker fest in the bay in a couple of weeks, registration is closed but bet you can get in if you email via - https://darpahackfest.com