Almost everything:
- Fire/Life Safety systems at the FBI hacked to sound anthrax alarms...
- Controlling tollways, traffic signage, cameras, and lighting simultaneously to try to kill Bruce Willis and Justin Long.
- Computers that blow up on cue, in the homes of hackers that COULDN'T see a chunk of C4 in the drive bays.
All done by half a dozen "hackers" in a 60 foot-long truck meandering through the streets of Washington without any police intervention
Oh, and the "LoJack" still works when the FBI agents track down the hackers, even though all of the infrastructure was allegedly destroyed.