I'm in the process of gradually enhancing my site's markup with microformats, in order to "indiewebify" my site further.
On thing I noticed while working on this at the Düsseldorf Indiewebcamp, is that WordPress (or the way my theme handles) tags on posts has no way to get an additional class inside the link markup. I noticed this while POSSEing to flickr -- my categories were transferred, my tags not so much, because the class="p-category" was missing. I found a way to modify the the_tags output by hooking into WP's term_links-$taxonomy filter in my theme's function.php.

Maybe there's a smarter way (actually I'm pretty sure there is a smarter way) than overriding a whole block of WP's `get_the_term_list function`, but this works for me, and well, isn't that the spirit of the whole IndieWebThang. :-)

In function.php:

function wbr_term_links_tag($links){
	global $post;
	$terms = get_the_terms($post->ID,'post_tag');
	if( is_wp_error( $terms ) ){
		return $terms;
	if( empty( $terms ) ){
		return false;
	$links = array();
	foreach ( $terms as $term ) {
		$link = get_term_link( $term, $taxonomy );
		if ( is_wp_error( $link ) ) {
        	return $link;
    	$links[] = '<a class="p-category" href="' . esc_url( $link ) . '" rel="tag">' . $term->name . '</a>';
	return $links;
add_filter('term_links-post_tag', 'wbr_term_links_tag' );

In the post-template:

  the_tags('', ', ', ' ');

And this puts out: <a class="p-category" href="https://www.webrocker.de/tag/dyi/" rel="tag">dyi</a>, which will provide the correct microformat class.

There are some points to remember, though: The function I'm hooking in is using a dynamic part to address which kind of taxonomy it deals with, as you can see on line 1244. So in order to target "tags" only, one needs to look up what the taxonomy name of that is, and surprisingly it is not "tags", but "post_tag", which needs to be added to the first parameter of the add_filter() call, and in the get_the_terms(); call inside the callback function.