Problem I had with the book is that he either misunderstood or misrepresented that triggering event. Yes, there were overgrown trees, high summer demand and temperatures that made power lines heat up and stretch. Wind speed dropped from 5 to 2 knots and cooled the line less than it normally did in that place. Cables stretched more than usual and grounded. These are all true facts.
However, that's not what brought the power grid down that day. Here's what did.
At 12:40 pm, an engineer working for MISO (transmission company, sort of like a traffic regulator) switched a regulation system to manual mode to make a correction. Note that the correction was made because the system had an errant piece of information regularly enough, which through a phone call the operator knew was false and corrected.
The regulation system was called a "state estimator." It basically takes tons of factors, loads, schedules, downtimes, capacities, etc and optimizes power transmission. Like intelligent traffic control. Of course, all systems have input garbage from time to time, and he corrected this thing.
At 1:30 PM that engineer went to lunch, forgetting to re-enable the automated mode.
At 2:02 PM, a 345k-volt line tripped after touching a tree and started this cascading reaction resulting in a system blackout for a week. Other operators looking at the system readouts didn't know that the state estimator was now sending a false picture, being frozen in manual mode.
By the time the unnamed engineer (from the NERC report) returned, it was too late. Other regulators, operators and power plants had been making uninformed decisions, preparations and adjustments for the power grid based on outdated, non-realtime information. However, the blackout didn't happen instantly -- it took four hours for a cascading chain reaction to trip every safety device in the system.
Lets not even go into SCADA vulnerabilities. Here's some positive outcomes from the blackout: investigators made a staggering list of 46 recommendations -- none addressing tree trimming because vegetation events happened all the time. Those were routine. They did focus on computer security, even though there were no computer faults in this incident.
Secondly, during the blackout the Department of Energy ordered state of Connecticut to energize one of their power plants despite their objections. They complied, and that restored power to metropolitan areas. This action is now a precedent for any future outage events: the legal framework for prioritizing power restoration exists and is in place.
SCADA systems show up on HN often enough to be a point of ridicule. Good news is that the outdated SCADA systems are getting replaced with synchrophasors for the most critical power integration functions. Since 2003, nearly 1700 phasors were added to the national grid, and they're well on their way to be fitted in the roughly 7,000 power plants in the U.S. What it will do over SCADA is improve recovery times of an unstable power grid segment.
Edit: derp, northeast, not nw. Also http://energy.gov/sites/prod/files/oeprod/DocumentsandMedia/...