Not only is the ability to create and edit Friend Lists available from the Facebook chat bar, but you can now control who sees you online via friend lists. Say you want to be on FbChat, but don't want your coworkers to see that you're online. Now you can simply exclude your co-workers friend list from chat and viola! - you're invisible to just them.
This type of control has never been available in FbChat, and is really only something that Facebook can do with its large social graphs and its useful friend lists feature. The ability to only have your favorite group of friends appear in chat and to control who sees you online is a significant advancement for the social network's IM product.
The new FbChat comes with two tabs in order to execute this functionality - Friend Lists, which is where you edit and display specific lists, and Options, which is where you can now change FbChat settings. To disappear from FbChat for a specific list, you just have to move in-chat sliders from the on position (green) to the off position (grey).