edit: It could be envo.lv http://news.ycombinator.com/item?id=2756145
It was always intended to be a marketing gimmick. The critical mass required to sustain good conversation only lasted for the time the story was on the front page.
Getting a website owner to install a chat system, (rather than just having an overlay) combined with integrating with site credentials will make an on-site chat system significantly more viable.
Make it a Facebook app as well that interacts with comments you've left on pages you like? Or post your chat comments to Facebook? I don't know what it is, but I would love to see it happen.