We’ve installed a new comment system called Disqus, which comes with lots of bells and whistles. It will allow you to log in using your Facebook, Twitter, or Google accounts if you want (though you can still just enter your name and email as a “guest,” as usual). It also allows you to “like” a particular page or a particular comment.
We’ll probably be tinkering with settings for a week or so until we figure out how everything works. Also, all of the old comments are queued up to be imported into the new system, so if your comments are missing, they should be back soon.