The tags-as-sections thing breaks down when you get a little more abstract than "x language", as the tags used will be ambiguous (people can retag stuff though, so that's something of a moderation system).
Granted, it's not that hard to do, but it's not optimal from a usability perspective.
For instance, PHP wasn't listed in the popular tags even though it's one of the top ten most popular programming languages (http://www.langpop.com/). To find this tag, I had to click Tags, search for PHP, and click PHP.
Php probably wasn't listed in the popular tags due partially to the windows/.NET tendency of the site, and the tendency of the people participating in the beta to be the type that doesn't like php.