I suppose this is okay, but it can quickly become a mess as soon as you need to make the modified portion of the dom interactive:

    $('#messages').prepend('<%=j render @message %>')
      .find('.delete').click(fn)
      .end().find('.reorder').hover(fn,fn)

I suppose they work around this problem with event delegation.

If you use something like angular, the whole mess becomes:

    $scope.messages.unshift(message);