<input type="text" value="{{inputValue}}" onblur={{action "toggleInputFocused"}} onfocus={{action "toggleInputFocused"}}>

valueChanged: Ember.observer('inputValue', function () {
  // deal with the change
  this.set("valueSet",(this.get('inputValue').trim().length > 0));
}),

{{input value=inputValue focus=(action "toggleInputFocused")}}