rollout.rb

before "deploy", :start_serenading
after "deploy", :stop_serenading

desc "Start serenading"
task :start_serenading do
  fork {`afplay '/path/to/rollout.mp3'`} rescue nil
end

desc "Stop serenading"
task :stop_serenading do
  system("killall -TERM afplay 2>/dev/null") rescue nil
end