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 ...