gistfile1.js

// the view:

NB.NavigationMenuView = SC.TemplateCollectionView.extend({
  
  layerId: 'navigation',
  classNames: ['navigation', 'modules-list'],
  contentBinding: 'NB.modulesController.content',

  itemView: SC.TemplateView.extend({
    templateName: 'navigation',

    submenu: SC.TemplateCollectionView.extend({
      contentBinding: '.parentView.content.menuItems',
      
      itemView: SC.TemplateView.extend({
        buttonPressed: function() {
          console.log(this.get('content')); // item is ready
        },
        
        hash: function() {
          console.log(this.get('content')); // item is BUSY_LOADING
          return '#!/' + this.getPath('content.hash'); // template just gets #!/undefined
        }.property('content')
      })
    })
  })

});

// the template:

<h3 class="head"><a>{{content.title}}</a></h3>
{{#collection submenu}}
  {{#view SC.Button action="buttonPressed"}}
    <a {{bindAttr href="parentView.hash"}}>{{parentView.content.title}}</a>
  {{/view}}
{{/collection}}