You can't do this at the moment without giving in an index in your helper, i.e

Template.yourtemplatename.object_with_index = function() {

    var objects = Template.yourtemplatename.objects();



    for(var i = 0; i=objects.length; i++) {

        objects[i].index = i;

    }



    return objects;

}

Then do:

{{#each object_with_index}}

    <p>This is number {{index}}</p>

{{/each}}

Not the prettiest way, but other variations would basically do the same thing under the hood (e.g if you used a map)