Problem
You want to deploy your Rails 3.0.3 in Dreamhost with capistrano, but even though you follow the steps from a previous post here, when you go to the application’s main page you still get an error:

500 Internal Server Error

Solution
Thanks to a blog post from Brendon Wilson here, the last missing piece from the puzzle in order to have your application running is to add the following line to the top of your deploy.rb file:

require 'bundler/capistrano'

and redo your cap deploy.

Thanks Brendon.