grouping by last name

<?php
$employeeQuery = new WP_Query(array('post_type' => 'professionals', 'meta_key' => 'prof_lastname', 'orderby' => 'meta_value', 'order' => 'ASC'))
    <?php $prevltr = ""; ?> /* holder variable so we know what our current letter is */
if(have_posts()) { while ( $employeeQuery->have_posts() ) { $employeeQuery->the_post(); ?>
    <?php $lastname = get_post_meta($post->ID, 'prof_lastname', true); ?> /* get the last name post meta */
    <?php $curltr = strtoupper(mb_substr(trim($lastname,0,1,'UTF-8'))?>
    <?php if($curltr != $prevltr) : ?> /* is our current letter different? */
      <?php echo $curltr; $prevltr = $curltr; ?> /* print out the current letter and update prevltr */
    <?php endif;

    /**
     * Just put what you want printed per employee here .... i.e. phone number name...
     */
<?php }} // End the loop. Whew. ?>