How Github uses Github to build Github
Every time I read one of these (Github, Etsy, ...), I feel a bit guilty that our tiny startup doesn't do continuous integration/deployment.  I mean, we git push to Heroku to deploy (maybe once a week), but there is no automated push once the tests pass.  It seems like this is a big psychological leap (deploy every week vs deploy every hour).When does setting up something like Jenkins CI become worth it?  When you have 2 people?  10 people?  100 people?Is there tons of custom code to set it all up with Github or whatever deployment scripts exist?  What CI systems are dominant?  (I'm mostly curious about Ruby-centric ones, but don't really want to bias responses.)