Here’s a little tidbit for you from the current Popular Mechanics on the August Blackout and the possibility of it having been a terrorist attack:

According to Charles E. Noble, head of Information Security for ISO New England, a NERC member that operates transmission lines, some sort of probing attack may have occurred during the appearance of the so-called "SQL Slammer Worm" that disrupted many Internet services. It also affected two unnamed utilities. "Both entities lost their ability to execute bulk electric system control from their primary control centers for several hours," Noble says.