The blackouts happened when California had a 55 megawatt capacity and 49 megawatt demand. It happened because the plant operators colluded to take about 20% of power generating capacity offline simultaneously.
I doubt we'll see that again, although I've heard that Homeland Security has required deactivating wind generation 'farms' on some flimsy security pretext. We do need another plant or two...
EDIT: not necessarily shutting down, but stopping creation of 15 wind turbine 'farms...'
http://www.physorg.com/news68373280.html
DHS's close ties to the oil industry couldn't have anything to do with that, of course.