We now have a Facebook-like Chat Bar and a new Group Chat with additional special features, located at the bottom of your web browser window.
You can also have one-on-one chats with your friends, in order to have them show up in your who's Online list, you will need to add them as friends using the "Add Friend" button when looking at their profile.
The original "Live Chat" button at the top will also directly link you into the chat area as well.
I have had to temporarily disable the new Chat system for a short time due to excessive load it has been putting on the server. It is currently being investigated with the chat vendor and with any luck, a solution should be put in place soon.