How can I derive the content of my select view from records in ember?

I have this:

App.LoginRegisterController = Ember.ObjectController.extend({
  init: function () {
    this.set('products', this.store.find('product'));
  },
  subscriptionOptions: function () {
    return this.get('products').map(function (product) {
      return {id: product.id, title: product.title};
    });
  }.property('products')
});

Then in my template:

{{view "Ember.Select"
content=subscriptionOptions
optionValuePath='content.id'
optionLabelPath='content.title'}}

However subscriptionOptions only get called once before the products are populated. If I change the template to:

{{view "Ember.Select"
content=products
optionValuePath='content.id'
optionLabelPath='content.title'}}

The data gets populated correctly, but I need to insert an option into the select that isn't related to any of the models, so I need to populated it with references. How can I get the select to update from subscriptionOptions as products change?