Hundreds of millions of users world-wide, billions of writes and trillions of reads per day -- Twitter operates at a scale that very few software systems ever achieve, and it must do so within the context of 'now'. Near real-time delivery of the relentless stream of tweets is one of Twitters highest architectural priorities, with tweets from Presidents, Popes, celebrities, scientists, and maybe even your mom, all being delivered to millions of followers within seconds. This talk will delve into the service-oriented-architecture we have developed at Twitter, some approaches we take for maintaining high levels of concurrency, and briefly touch on some functional design patterns we employee to manage code complexity in a rapidly evolving system.