<script type="text/x-handlebars">
  <p>
    <label>What is your name?</label>
    {{input type="text" value=name}}
  </p>
  <p><strong>
    {{#if name}}
      {{shout}}
    {{else}}
      I WILL SHOUT YOUR NAME!
    {{/if}}
  </strong></p>
</script>

App = Ember.Application.create();

App.ApplicationController = Ember.Controller.extend({
  name: '',
  shout: function() {
    return 'HELLO ' + this.get('name').toUpperCase() + '!';
  }.property('name')
});