Any metrics you can share about the team size, any esoteric skill sets found to be crucial, or overall cost? Some sense for those who wonder "what would it take to create or recreate something like this?"
One big advantage we have that speeds up development is the Facebook culture of moving fast and shipping often. Facebook employees are used to working with software as it's being built and refined. This kept us focused on the key subset of features that matter to users and getting close to realtime feedback from them. Our development cycle is typically one release and push to production per week.
Also, from the beginning Presto had to work with current Facebook infrastructure (100s of machines, 100s of petabytes), so we faced and solved all the associated scaling challenges up-front.