gistfile1.js

Template.gem_view.context = function() {
  return {
    contentTemplate: "gems"
  };
};

Template.page.render_content = function() {
  var context = this;
  var html = Template.no_template_found;
  if (context && context.contentTemplate) {
    if (typeof Template[context.contentTemplate] !== "undefined") {
      html = Template[context.contentTemplate];
    }
  }
  return html;
}

/* here is the template for the code above */
<template name="page">
    {{{render_content context}}}
</template>