WP-FacebookConnect adds Facebook functionality to WordPress using the Facebook Connect APIs. It provides single sign-on, avatars, and News Feed publication of comments.

via WP-FBConnect – Facebook Developers Wiki

So this is how Techcrunch and others are allowing people to comment with their facebook account. Its nice to see that its open source. Looks like the installation is fairly manual, but that shouldn’t be a problem for most people.

I found this plugin that might also be good. Facebook Connect WordPress Plugin.