Kresten Krab Thorup discusses data models for Riak, a protocol for synchronizing key-values, and BucketDB, a mobile Riak client.
Justin Sheehy talks about failure and the need to prepare for it, giving some real life examples along with techniques implemented in Riak to make it resilient to faults.
Bryan O'Sullivan discusses the design considerations and types usage when building distributed systems with Haskell and Riak, starting from a case study of a system using vector clocks.
Andy Gross discusses the design philosophy behind Riak based on Amazon Dynamo - Gossip Protocol, Consistent Hashing, Vector clocks, Read Repair, etc. -, overviewing its main features and architecture.