Railtie to perform Rails 3 initialization

lib/delayed/railtie.rb

@@ -0,0 +1,17 @@
+require 'delayed_job'
+require 'rails'
+
+module Delayed
+  class Railtie < Rails::Railtie
+    initializer :after_initialize do
+      Delayed::Worker.backend ||= if defined?(ActiveRecord)
+        :active_record
+      elsif defined?(MongoMapper)
+        :mongo_mapper
+      else
+        Delayed::Worker.logger.warn "Could not decide on a backend, defaulting to active_record"
+        :active_record
+      end
+    end
+  end
+end

lib/delayed_job.rb

@@ -4,6 +4,7 @@
 require File.dirname(__FILE__) + '/delayed/performable_method'
 require File.dirname(__FILE__) + '/delayed/backend/base'
 require File.dirname(__FILE__) + '/delayed/worker'
+require File.dirname(__FILE__) + '/delayed/railtie' if defined?(::Rails::Railtie)
 
 Object.send(:include, Delayed::MessageSending)   
 Module.send(:include, Delayed::MessageSending::ClassMethods)