Big things to do when deploying a rails app

In the question What little things do I need to do before deploying a rails application I am getting a lot of answers that are bigger than "little things". So this question is slighly different.

What reasonably major steps do I need to take before deploying a rails application. In this case, i mean things which are are going to take more than 5 mins, and so need to be scheduled. For small oneline config changes, please use the little things question.