Finally got around to adding Technorati tags to the site, via a rather roundabout (yet simple) way - they're generated from the Wiki links present on a page (which is the only real way to do it in a Wiki, partly because I can't be bothered to manually tag each post), and are only visible through the Atom and RSS feeds (purists will like to know that due to ancient PhpWiki internals, I could not use the category attribute in the feeds - I will fight that battle another night).
I personally find that they add too much clutter between posts on a standard web page, but since feed aggregators tend to show one article at a time, that may be more acceptable.
Update: João Craveiro pointed out that single-page views of a node might also be suitable to display the tags, but they are already conveniently present in both the Wiki links and the SeeAlso footer for each individual Wiki node (I'm using rel="tag" on those).
Anyway, in case your aggregator supports CSS, you can style the div containing the tag links through a class called (unimaginatively) technorati_tags. Someday I will get around to add a CSS to the actual feeds, but for now it's just right-aligned on a per-instance basis.
In the meantime, I've been wondering if Technorati indexing is working at all - even after pinging them some twelve hours ago, there is still a single match for Confluence, for instance (which is both a recent post and a fairly uncommon tag).