A simple Handlebars helper to do automatically updating dates. Requires moment.js

post_view.hbs

<time>{{timeAgoInWords post.publishedAt}}</time>

time_ago_in_words_helper.js

(function() {
Ember.Handlebars.registerHelper('timeAgoInWords', function(property, options) {
  var data = options.data,
      view = data.view,
      currentContext = (options.contexts && options.contexts[0]) || this,
      pathRoot, path, normalized;

  normalized = Ember.Handlebars.normalizePath(currentContext, property, data);

  pathRoot = normalized.root;
  path = normalized.path;

  var bindView = new Ember._SimpleHandlebarsView(
    path, pathRoot, !options.hash.unescaped, options.data
  );

  bindView.normalizedValue = function() {
    var value = Ember._SimpleHandlebarsView.prototype.normalizedValue.call(bindView);

    return function(value, options) {
      // This returns the value to actually render.
      return moment(value).fromNow(false);
    }.call(view, value, options);
  };

  view.reopen({
    didInsertElement: function() {
      var self = this;

      if (this.updateTimer) { clearTimeout(this.updateTimer) };

      this.updateTimer = setInterval(function() {
        if (self.state === 'inDOM') {
          Ember.run.scheduleOnce('render', bindView, 'rerender');
        }
      }, 10000);
    },

    willDestroyElement: function() {
      if (this.updateTimer) { clearTimeout(this.updateTimer) };
    }
  });

  view.appendChild(bindView);

  observer = function() {
    Ember.run.scheduleOnce('render', bindView, 'rerender');
  };

  Ember.addObserver(pathRoot, path, observer);

  view.one('willClearRender', function() {
    Ember.removeObserver(pathRoot, path, observer);
  })
});

})()

Bugs: 30&40th line if (this.updateTimer) { clearTimeout(this.updateTimer) }; should be if (this.updateTimer) { clearTimeout(this.updateTimer); } and 54th line misses a semicolon ;.