The snippet for config/deploy.rb to use Bundler.

capistrano-with-bundler-deploy.rb

# use this in a after "deploy:update_code" block

namespace :bundler do
  task :create_symlink, :roles => :app do
    shared_dir = File.join(shared_path, 'bundle')
    release_dir = File.join(current_release, '.bundle')
    run("mkdir -p #{shared_dir} && ln -s #{shared_dir} #{release_dir}")
  end

  task :bundle_new_release, :roles => :app do
    bundler.create_symlink
    shared_dir = File.join(shared_path, 'bundle')
    run "cd #{release_path} && bundle install --path #{shared_dir} --without test development"
  end

  task :lock, :roles => :app do
    run "cd #{current_release} && bundle lock;"
  end

  task :unlock, :roles => :app do
    run "cd #{current_release} && bundle unlock;"
  end
end

Marko,
Which of these tasks will need to be run after each deployment?

nevermind, I RTFM and figured that out. But a better question is when to lock and unlock. You lock after you do a bundle install and unlock only when you are changing your Gemfile and redeploying?

I don't ever do anything to Gemfile.lock - Bundler changes it itself when you do a bundle install and a newer version of something is available, or you add a new dependency to Gemfile.