Over the last few months there have been numerous reports about a new, fully revamped Facebook commenting plugin that would make the social network a viable competitor to the likes of Disqus, Echo, and the stock comment engines found in WordPress and other CMS platforms. Well, the reports were true, and today Facebook is lifting the curtain on its big new comments platform. If you want to get a taste of them, look down — we’re currently testing them on TechCrunch.

Now let’s take a look at what makes this interesting. First, you’ll notice that if you’re already logged into Facebook, you won’t have to click though any authentication options. More important, you’ll notice that any comments you write are being left under your real name, which spells bad news for you trolls and spammers. And then there are the viral Facebook-centric features that other comment engines simply can’t compete with.

Whenever you leave a comment on a site that’s using Facebook comments, you’ll see a checkbox asking if you’d like to also post that comment to Facebook. Leave it checked (it is by default), and your comment will be posted on your Facebook Wall and in your friends’ News Feeds. That’s nice, but plenty of other sites let you syndicate content to your Facebook profile. But Facebook is also giving its own comments engine a feature that nobody else can reproduce: comments can be syndicated the other way.

Let’s say I leave a comment on TechCrunch and opt to have that comment shared to Facebook, too. Then, if one of my Facebook friends comes along and leaves a comment on Facebook about my comment, their comment will be posted back to TechCrunch. In other words, any discussion that my comment sparks between my Facebook friends will be seen on TechCrunch as well. That’s very powerful, and it’s something that nobody else can do.

This is the first time Facebook has enabled this kind of automatic external posting (historically everything you’ve posted on Facebook has stayed on Facebook). The company says that it’s making it clear what’s going on — you’ll notice in the photo above that the button users click actually says which site they’ll be posting to. But, given that this is a new experience on the site, I’m sure we’ll encounter some people who inadvertently have their comments posted to third-party sites.

Aside from the sharing features, Facebook is using its social algorithms to surface the comments that will be most interesting to you — comments left by your Facebook friends will float to the top. Comments will also be sorted according to how much discussion they’ve sparked (this sounds a lot like the sorting feature in Facebook’s new Pages update). Incidentally, it’s also now possible to leave a comment on an external site as a Facebook Page, which means we could see brands use Facebook to leave ‘official’ comments on blog posts.

The new comments system also includes many of the administrative options you’d expect. Admins can moderate comments, and readers can mark posts as spam, and so on. And integrating this with a site should be straightforward: Facebook says it just takes adding a single line of code.