On the internet, there seems to be two kinds of information available to do with "scaling rails", or on "scaling" in general.
Blog posts about how the really big boys are doing things
Blog posts full of non-production benchmarks explaining why you need a particular data store, templating framework, or anything else to be "web-scale"
This talk will hopefully be a third kind, practical advice to help you grow your application at the right pace alongside your business' growth, based on real world experience.
Topics covered will (probably) include:
Why you should probably choose Postgres or Mysql as your data store
Why going from one developer to two developers is the hardest
Why going from one server to two servers is the hardest
Why those two things are actually the same problem
How YAGNI and SRP apply to your hosting just as much as your code
How you balance your cost-speed-quality stool for developing your app up against the same cost-speed-quality tripod for your infrastructure
Why other people's advice on the topic can only ever provide a starting point, not a final answer