Edit in JSFiddle

App = Ember.Application.create();

App.CustomCircleLayer = EmberLeaflet.CircleLayer.extend({
    optionsBinding: 'content.options'
})
App.CircleCollectionLayer = EmberLeaflet.CollectionLayer.extend({
  contentBinding: 'controller',
  itemLayerClass: App.CustomCircleLayer
});

App.MarkerCollectionLayer = EmberLeaflet.MarkerCollectionLayer.extend({
  contentBinding: 'controller'
});




App.IndexView =
  EmberLeaflet.MapView.extend({
    center: L.latLng(40.7189000170401, -73.9944648742675),
    zoom: 14,
    childLayers: [
      EmberLeaflet.DefaultTileLayer,
      App.MarkerCollectionLayer,
      App.CircleCollectionLayer
    ]});

App.IndexController = Ember.ArrayController.extend({
  content: [
      {location: L.latLng(40.714, -74.000), radius: 1000, options: {color: '#000', fillColor: 'red'}},
    {location: L.latLng(40.714, -73.989), radius: 300},
    {location: L.latLng(40.721, -73.991), radius: 100}]
 });

<script type="text/x-handlebars" data-template-name="application">
    {{outlet}}
</script>

.leaflet-container {
    position: absolute;
    top: 0; left: 0; bottom: 0; right:0;
}