Enjoyed the slides. There is a key difference between this design and the design posted by netflix (
http://techblog.netflix.com/2011/04/lessons-netflix-learned-...) in that netflix treats their NoSQL db (Cassandra) as ephemeral, runs it on ephemeral storage, and uses s3 for durability.
If there anyone who could provide a pointer to someone describing a setup running relational dbs on ephemeral storage with s3 for durability I would be very interested.