Tags are now live: You can apply them by typing them into the box below the entry area, separated by commas. The tags you type in will also stay across posts, so if you're making a series of posts on the same topic, you don't have keep typing them again and again.
Tags appear along the bottom right of each post, and clicking on them will show you posts with that tag only.
Each tag is limited to 20 characters each, with up to 5 tags per post. One thing I'm trying out here is the possibility of creating tags languages other than English. Keep in mind that they need to go into the URLs too, so let's see how that works out.