Sounds like people are having trouble getting it to work.
For it to work you will need to have Java installed on your computer.
You can download it here: http://java.com/en/download/index.jsp
It's a free, harmless program that allows you to run small applications online. If you already have it installed, it could be your browser settings or some kind of firewall that's blocking it.
Also, when you go to the chat, you should get a popup window that asks if you want to load the applet. You have to click Yes.
If all else fails, you can always just download a program like mIRC and access the chat channel manually.