Facebook, in the footsteps of Disqus, is exporting its comments system so websites can use it as a third party plug-in for a comments section. To use the feature, users would be able to log in via Facebook or Twitter to leave their comments. This is convenient for those that don't like to register on every single website they visit. Comments are threaded and you can reply to or 'like' others' comments. Comments can be synced on to the websites' Facebook pages, so comments made on a website can also show up on their Facebook page. However, it doesn't seem to work both ways.
This tie up seems to feed Facebook more than the website itself. If someone makes a mention of the website's Facebook page and references an article in their status update, that information won't necessarily show up on the website itself. Disqus does provide this service. For instance, Disqus will sync the website's twitter account to the articles on the site so if someone's made a mention of the article on Twitter, Disqus will pick it up and place it in the article's comments section.