If you would like to read postmortems, I maintain a list of them here (over 250 so far): https://pinboard.in/u:peakscale/t:postmortem/
In a similar vein is the Google+ Postmortems community: https://plus.google.com/u/0/communities/11513614020301839179...
It would be fantastic to take this set visualise their causes. It would be really interesting to see whether the causes are that different for large corporations vs smaller startups. I suspect, as in the article, it remains that configuration, error handling and human causes are still the most popular regardless of whether you have vast quantities of process or money for tooling.