rails3-jquery-autocomplete in ActiveAdmin?

active_admin.rb

ActiveAdmin.setup do |config|
  #...
  config.register_javascript 'autocomplete-rails.js'
end

appadminflights.rb

ActiveAdmin.register Flight do
  #...
  controller do
    autocomplete :pilot, :name, :full => true
  end

  form do |f|
    f.input :pilot_name, :as => :autocomplete, :url => autocomplete_pilot_name_flights_path
  end
end

Gemfile

source 'http://rubygems.org'

gem 'rails3-jquery-autocomplete'

routes.rb

Cpr::Application.routes.draw do
  #...
  resources :flights do
    get :autocomplete_pilot_name, :on => :collection
  end
end

If you're using the jquery-ui gem,
don't forget to add the jquery.ui.theme.css file to active_admin stylesheets:

In config/active_admin.rb:
config.register_stylesheet 'jquery.ui.theme.css'