Converted to config option, thanks to Roy!

app/models/observer/user/geo.rb

@@ -1,5 +1,4 @@
 # Copyright (C) 2012-2013 Zammad Foundation, http://zammad-foundation.org/
-require 'gmaps'
 
 class Observer::User::Geo < ActiveRecord::Observer
   observe 'user'
@@ -54,8 +53,13 @@ class Observer::User::Geo < ActiveRecord::Observer
     # return if no address is given
     return if address == ''
 
+    # load adapter
+    adapter = Setting.get('geo_backend')
+    return if !adapter
+    adapter_module = Object.const_get(adapter)
+
     # db lookup
-    latlng = Gmaps.geocode(address)
+    latlng = adapter_module.geocode(address)
     return if !latlng
 
     # store data

config/application.rb

@@ -40,9 +40,9 @@ module Zammad
       'observer::_ticket::_article::_communicate_facebook',
       'observer::_ticket::_article::_communicate_twitter',
       'observer::_ticket::_notification',
-      'observer::_tag::_ticket_history',
       'observer::_ticket::_reset_new_state',
       'observer::_ticket::_escalation_calculation',
+      'observer::_tag::_ticket_history',
       'observer::_user::_geo'
 
 

db/migrate/20130806000001_update_geo.rb

@@ -0,0 +1,29 @@
+class UpdateGeo < ActiveRecord::Migration
+  def up
+    Setting.create_if_not_exists(
+      :title       => 'Geo Location Backend',
+      :name        => 'geo_backend',
+      :area        => 'System::Geo',
+      :description => 'Defines the backend for geo location lookups.',
+      :options     => {
+        :form => [
+          {
+            :display  => '',
+            :null     => true,
+            :name     => 'geo_backend', 
+            :tag      => 'select',
+            :options  => {
+              '' => '-',
+              'Gmaps' => 'Google Maps',
+            },
+          },
+        ],
+      },
+      :state    => 'Gmaps',
+      :frontend => true
+    )
+  end
+  def down
+  end
+end
+

db/seeds.rb

@@ -133,7 +133,28 @@ Setting.create_if_not_exists(
   :state       => 'DB',
   :frontend    => false
 )
-
+Setting.create_if_not_exists(
+  :title       => 'Geo Location Backend',
+  :name        => 'geo_backend',
+  :area        => 'System::Geo',
+  :description => 'Defines the backend for geo location lookups.',
+  :options     => {
+    :form => [
+      {
+        :display  => '',
+        :null     => true,
+        :name     => 'geo_backend', 
+        :tag      => 'select',
+        :options  => {
+          '' => '-',
+          'Gmaps' => 'Google Maps',
+        },
+      },
+    ],
+  },
+  :state    => 'Gmaps',
+  :frontend => true
+)
 
 Setting.create_if_not_exists(
   :title       => 'New User Accounts',