widgets.html

{{#if widgetsLoading}}
  <p>loading widgets...</p>
{{else}}
  {{#ifAny widgets}}
    {{#each widgets}}
      <p>Name: {{name}}</p>
    {{/each}}
  {{/ifAny}}
{{/if}}

widgets.js

Session.set('widgets.loading', true);
Meteor.subscribe('widgets', function() {
  Session.set('widgets.loading', false);
});

Template.widgets.widgetsLoading = function() {
  return Session.get('widgetsloading');
};