I'm one of the lucky people who have to wait. The airport personnel tells us it's the system that prints out weather information that's out. Not sure why one would want to attack that.
Assuming what you've heard is correct this seems to span multiple Delta systems.
http://qz.com/417617/every-united-airlines-flight-was-ground...
and again http://www.pcworld.com/article/2945552/united-airlines-fligh...
and again http://newyork.cbslocal.com/2016/05/29/computer-system-shuts...
Well, that would make it less obvious.
1. Take a short-position on Delta on the stock exchange
2. Sabotage a piece of infrastructure that's important to operations
3. ???
4. Profit!
:)