At Centzy, we evaluated FoundationDB for several months. Impressive technology (horizontally scalable key-value store with transactions and failover), its fast, and it just works. We were initially concerned about using a proprietary datastore built by another startup, but after having lunch with Dave and Andrew, we decided we had to use them. One of my favorite things was how they sometimes responded to support requests with code.
FoundationDB co-founder here. We're pretty psyched about this acquisition and the technical fit between our storage substrate and Akiban's open-source SQL tech.