A workaround for skipping Rails asset pipeline compilation in Capistrano 2 and avoid to compile asset on servers.

deploy.rb

# Comment load 'deploy/assets' in Capfile
# Usage
# cap deploy -> deploy with asset pipeline compilation
# cap deploy -s skip_asset=true -> deploy without asset pipeline compilation, just keep the old asset

namespace :deploy do
  task :default do
    update
    # migrate # uncomment this when you need to run migrations
    assets.precompile
    restart
    cleanup
  end
end

namespace :assets do
  desc "Precompile assets locally and then rsync to app servers"
  task :precompile, :only => { :primary => true } do
    run "cp -R #{File.join(previous_release, 'public', 'assets')} #{current_path}/public/assets"
    unless exists?(:skip_asset)
      run_locally "bundle exec rake assets:clean; bundle exec rake assets:precompile;"
      servers = find_servers :roles => [:app], :except => { :no_release => true }
      servers.each do |server|
        run_locally "rsync -av ./public/assets/ #{user}@#{server}:#{current_path}/public/assets/;"
      end
      run_locally "rm -rf public/assets "
    end
  end
end

The only problem is that you can't run deploy:migrations it's a workaround! to run migrations just uncomment line 9 and deploy!