At Semiocast, a start-up founded in 2009, we use Erlang since day one to fetch and process millions of tweets and social media conversations. In this talk, we will present lessons we have learned in terms of code deployment, architectural design, Erlang technologies used and integration with native code. In particular, we will cover how we use OTP and code change, the various kinds of drivers (NIF, Linked-In, External, C-node), our usage of HiPE and dialyzer, and a few things we wish we knew back in 2009.