I'm always put off by the "look what can be done in just several lines!" code examples on frameworks front pages, they don't represent anything about the framework and usually the simpler the example, the more complex the framework is because everything is "magic" - try to do something differently and you end up hacking the framework internals.
It's especially offending when, as in this case, the bragging code-snippet omits half of the code that is needed to actually run the demo.
Ember is far from the only project guilty of this.
If you want to brag to me then make sure I can copy/paste your example to a file and it will run. I'll take a honest 50-liner over a dysfunct 10-liner any day.