There is a happy occasion in the development of an application ��� deployment. Users will use it, you will receive (hopefully) some money, there will be some bugs.. well, maybe not so happy occasion.. ;>
In most situations you will have to repeat a deployment process several times (bug fixes, new features, etc.). Maybe the process is not very complicated, but an automation will mimise possible mistakes such as typos or omitted commands.
Fortunately, there is a nice tool for Ruby on Rails applications ��� Capistrano.