automatically including a plugin/gem's module in rails

Question

I have a gem that I'm working on that contains a module that I'd like to be automatically included in my Rails app. For now, I've put the following:

config.after_initialize do
  include MyModule
end

I'd like to not have to include this in the instructions for my app. It would be great if someone could install the gem/plugin and have this happen automatically. Is there a way to do this?