The rails-bootstrap application is on GitHub.
Generate a starter app in minutes using an application template:
$ rails new rails-bootstrap -m https://raw.github.com/RailsApps/rails-composer/master/composer.rb
You get a Rails application with Twitter Bootstrap. Customize as you wish.
Get the tutorial (subscription required) for an in-depth introduction to Rails and Twitter Bootstrap. Subscriptions provide financial support for the RailsApps project.