New tags show up in the 10k tools (in the "stats" link). So they aren't moderated before being created, but the information is available to higher-rep users. Also in the tools you can see what's been recently protected, closed, reopened, deleted, or undeleted, and which posts are attracting the most votes, views, and comments. It's pretty handy as a way to get a quick "highlights" view of recent activity.
Most things on Stack Exchange are not moderated before the fact. Edits are because they're a source of spam, but just as new posts and comments don't need to be approved first, new tags don't. In all of these cases the philosophy is to let the material get posted first and then, if needed, the community can act on it. Communities count on the 10k users to do these reviews from time to time; if crap is getting through on your site, it's probably time to remind people that their help is needed (on meta or in chat).