auth.js

App.AuthController = Ember.Controller.extend({
  // isGuest: true,
	observeIsGuest: function() {
		console.log('isGuest changed: ' + this.isGuest);
	}.observes('isGuest'),
    login: function() {
			self.set('isGuest', false);
		});
	},
	logout: function() {
			self.set('isGuest', true);
	},
	checkLogin: function() {
		var self = this;
		var response = $.Deferred();
		$.ajax({
			url: '/users/me',
			type: 'GET'
			//contentType: 'application/json',
		}).done(function(data) {
			response.resolve(data);
			console.log('done checking');
			if (typeof data === 'undefined') {
				self.set('isGuest', true);
			} else {
				self.set('isGuest', false);
			}
		}).fail(function(xhr, status, error) {
			console.log(xhr.responseText);
			response.reject();
		});
		return response.promise();
	}
});

router.js

App.ApplicationRoute = Ember.Route.extend({
	beforeModel: function(transition) {
		this.controllerFor('auth').checkLogin().done(function(){
			transition.retry();
		});
	}
});

App.GuestRoute = Ember.Route.extend({
	redirect: function() {
		if(!this.controllerFor('auth').get('isGuest')){
			this.transitionTo('index');
		}
	}
});

App.AuthRoute = Ember.Route.extend({
	redirect: function() {
		if(this.controllerFor('auth').get('isGuest')){
			this.transitionTo('index');
		}
	}
});

/* Guest Routes */

App.LoginRoute = App.GuestRoute.extend({
	renderTemplate: function() {
		this.render({ controller: 'auth' });
	},
	setupController: function(controller, model) {
		this.controllerFor('auth').reset();
	},
});

/* Auth Routes */

App.LogoutRoute = App.AuthRoute.extend({
	setupController: function(controller, model) {
		this.controllerFor('auth').logout();
	}
});