Akamai's Prolexic platform was able to mitigate the attack by filtering all traffic sourced from UDP port 11211, the default port used by memcached.
Interesting. The impressive part is that their platform correctly identified the attack and automatically applied the solution within 20 minutes. I wonder how?
Possibly a team of smart sysadmins on standby? It's easy to detect when you're being attacked, but hard to mitigate. So whenever you get attacked, set up your site to automatically forward over to this service, and their clever humans take it from there.
Some of the most impactful tech projects are just mechanical turks, so it wouldn't be surprising. But I wonder what the truth is.