I work for Cisco and in the past I have worked in the Cisco TAC supporing routing protocols. That does not make me an expert but I'm not totaly clueless either.

I am not privy to what caused the outage. From the description I assume that it is likely that it was a routing protocol convergence issue.

This could have been caused by a bug or perhaps a mistake in configuration or poor design or a combination of the above.

I have seen large outages caused by configuration issues. What happens is a huge number of routes and alternative paths are dumped into the forwarding table and routers run of memory causing more mayhem and the whole network melts.

I am not saying that was the cause of this outage of course but until the cause is determined I would ask that people hesitate before afixing blame.