例：タームリスト

<?php
$taxonomies = get_post_taxonomies();
$terms = wp_get_object_terms( $post->ID, $taxonomies );
if( !empty( $terms ) ){
	$no = 0;
	$last = count( $terms ) - 1;
	foreach( $terms as $term ){
		switch ($no++) {
			case 0:
				echo 'first-'.$term->slug;
			break;
			case $last;
				echo ' last-'.$term->slug;
			break;
			default:
				echo ' middle-'.$term->slug;
			break;
		}
	}
}
 ?>