Verified answer

Everyone you usually interact with, online or not, which is STUPID, in my opinion, they also got rid of scrolling, so you have to search for a friend to talk to him/her if it doesn't show up :( (btw, only popout chat can have scrolling at least: http://www.facebook.com/presence/popout.php)

New chat box is designed to show only people who were you most chatting with. So it's going to be a bit frustrating, but we'll get over it just like on YouTube.