Chat is now on IRC. You can use the simple chat here or whatever IRC client you like.
Ports: 5000, 6666-6669, 7000, 6697 [SSL]
If you want to keep your nickname you should register it. Send the following command:
/MSG NickServ REGISTER password email
(replacing password with your password and email with a real email address you have access to. NickServ will send you a verification email with instructions.)