Process "Lastname, Firstname" in post titles.

firstname-lastname.php

<?php

/**
 * Processing "Last name, First name" pairs
 *
 * @param string $nom_prenom : The original post title ("Wilde, Oscar").
 *
 * @return string : The human-readable title ("Oscar Wilde").
 * 
 * Usage in theme: 
 * $post_title = firstname_lastname(get_the_title());
 *
 */

function firstname_lastname($post_title) {
	
  $pos = strpos($post_title, ",");
      		
  if ($pos === false) {
    // nothing to do.
  } else {
    $fir = explode( ",", $post_title ); 
    unset( $fir[0] ); 
    $end = ltrim( implode( ",", $fir ) ); 
    $first_name = substr($post_title, 0, $pos);
    $pos++;
    $post_title = substr($post_title, $pos) . ' ' . $first_name;
  }
	
  return $post_title;
}

An updated version of this method: https://gist.github.com/ms-studio/3928828