David Pick’s talk at the conj is about Kafka, which is a distributed messaging system. It implements a publish/subscribe model and runs in a cluster. Its documentation claims that Kafka has very high throughput.
Why it matters
Braintree, where David Pick works, is a huge payment processor, now owned by PayPal. They must have very strict availability and consistency requirements in addition to the scale. The talk description hints that Clojure was helpful to their success. Some of the best talks I’ve seen are this kind of experience report.