Tell devise that :mobile is a navigational format.

app/controllers/sessions_controller.rb

@@ -6,22 +6,12 @@ class SessionsController < Devise::SessionsController
 
   after_filter :enqueue_update, :only => :create
 
-  def create
-    resource = warden.authenticate!(:scope => resource_name, :recall => "#{controller_path}#new")
-    set_flash_message(:notice, :signed_in) if is_navigational_format?
-    sign_in(resource_name, resource)
-    redirect_loc = redirect_location(resource_name, resource)
-    respond_with resource, :location => redirect_loc do |format|
-      format.mobile { redirect_to root_path }
-    end
-  end
-
   protected
   def enqueue_update
     if current_user
-      current_user.services.each{|s|
+      current_user.services.each do |s|
         Resque.enqueue(Job::UpdateServiceUsers, s.id) if s.respond_to? :save_friends
-      }
+      end
     end
   end
 end

config/initializers/devise.rb

@@ -4,6 +4,15 @@
 
 # Use this hook to configure devise mailer, warden hooks and so forth. The first
 # four configuration values can also be set straight in your models.
+
+class ActionController::Responder
+  def to_mobile
+    default_render
+  rescue ActionView::MissingTemplate => e
+    navigation_behavior(e)
+  end
+end
+
 Devise.setup do |config|
   # Configure the e-mail address which will be shown in DeviseMailer.
   if AppConfig[:smtp_sender_address]
@@ -27,7 +36,7 @@ Devise.setup do |config|
   # authenticating an user, both parameters are required. Remember that those
   # parameters are used only when authenticating and not when retrieving from
   # session. If you need permissions, you should implement that in a before filter.
-   config.authentication_keys = [ :username ]
+  config.authentication_keys = [:username]
 
   # Tell if authentication through request.params is enabled. True by default.
   # config.params_authenticatable = true
@@ -130,6 +139,7 @@ Devise.setup do |config|
   # If you have any extra navigational formats, like :iphone or :mobile, you
   # should add them to the navigational formats lists. Default is [:html]
   # config.navigational_formats = [:html, :iphone]
+  config.navigational_formats = [:"*/*", "*/*", :html, :mobile]
 
   # ==> Warden configuration
   # If you want to use other strategies, that are not (yet) supported by Devise,

spec/controllers/sessions_controller_spec.rb

@@ -24,23 +24,39 @@ describe SessionsController do
   end
 
   describe "#create" do
-    it "redirects to / for a normal user" do
+    it "redirects to / for a non-mobile user" do
       post :create, {"user" => {"remember_me" => "0", "username" => @user.username, "password" => "evankorth"}}
       response.should redirect_to root_path
     end
+
     it "redirects to / for a mobile user" do
       @request.env['HTTP_USER_AGENT'] = 'Mozilla/5.0 (iPhone; U; CPU iPhone OS 4_1 like Mac OS X; en-us) AppleWebKit/532.9 (KHTML, like Gecko) Version/4.0.5 Mobile/8B117 Safari/6531.22.7'
       post :create, {"user" => {"remember_me" => "0", "username" => @user.username, "password" => "evankorth"}}
       response.should redirect_to root_path
     end
+
     it 'queues up an update job' do
       service = Services::Facebook.new(:access_token => "yeah")
       @user.services << service
-      @user.save
-      
       Resque.should_receive(:enqueue).with(Job::UpdateServiceUsers, service.id)
-      post :create, {"user"=>{"remember_me"=>"0", "username"=> @user.username,
-                               "password"=>"evankorth"}}
+
+      post :create, {"user" => {"remember_me" => "0", "username" => @user.username, "password" => "evankorth"}}
+    end
+  end
+
+  describe "#destroy" do
+    before do
+      sign_in :user, @user
+    end
+    it "redirects to / for a non-mobile user" do
+      delete :destroy
+      response.should redirect_to root_path
+    end
+
+    it "redirects to / for a mobile user" do
+      @request.env['HTTP_USER_AGENT'] = 'Mozilla/5.0 (iPhone; U; CPU iPhone OS 4_1 like Mac OS X; en-us) AppleWebKit/532.9 (KHTML, like Gecko) Version/4.0.5 Mobile/8B117 Safari/6531.22.7'
+      delete :destroy
+      response.should redirect_to root_path
     end
   end
 end