RailsPushQueues
This project rocks and uses MIT-LICENSE.
You can easily use Resque and/or Sidekiq workers without change.
Set Iron configs
In the environment config file, set:
config.iron_token = 'X'
config.iron_project_id = 'Y'
Register the workers
This is basically creating queues for each worker and setting your application as the subscriber.
rake queues:subscribe ImageConversionWorker