How do you render a view from within a handlebars helper that takes dynamic content?

This will work:

App.Label = Ember.View.extend({
  tagName: "span",
  classNames: "label",
  template: Ember.Handlebars.compile("{{view.content}}")
});

Ember.Handlebars.registerHelper('bslabel', function(content, options) {
  options.hash.content = content;
  return Ember.Handlebars.helpers.view.call(this, App.Label, options);
});

registerHelper takes each argument given to the view helper and a final options object. If you use Ember.Handlebars.helpers.view.call like a lot of the internal views in Ember, options.hash will be the properties given to that view. So in this case we take the content given as the second argument to our {{bslabel}} helper, and set it as the content property of the view.

You need to put the content in quotes for this implementation to work:

{{bslabel "Label content goes here"}}