Using :after pseudo class
You can use a special attr like this : see this topic
hr.style-eight:after {
    content: attr(data-date) ;
}
And in HTML
<hr class="style-eight" data-date="24-10-2013">
Thanks to this system, you are able to manipulate the content like you want... With some JS maybe, or with PHP using echo date("Y m d") (don't forget to set the timezone, something like date_default_timezone_set('America/New_York');) function.
And with jQuery : see here for date
$(document).ready(function() {
   var today = new Date();
   var dd = today.getDate();
   var mm = today.getMonth()+1; //January is 0!
   var yyyy = today.getFullYear();
   if(dd<10){dd='0'+dd;}
   if(mm<10){mm='0'+mm;}
   today = yyyy+' '+mm+' '+dd;//like you want ^^ (%Y %m %d)
    $('hr.style-eight').attr('data-date', today);
});
Using PURE HTML and no pseudo class :after
Another way without the use of :after pseudo class : Online example
hr.style-eight+span { 
  display: inline-block; 
  position: relative; 
  top: -0.7em; 
  font-size: 1.5em; 
  padding: 0 0.25em; 
  background: white;
}
And in the HTML
<hr class="style-eight" />
<span>2013 10 24</span>