Right now I click on the window to get the chat up, then I see the space to put in my username, but there is nothing else to do after that, no button to push to join. Guess they are closed now?
I downloaded the latest java client, so I don't know what is the problem.
I couldn't either today Cherno, go into your history from yesterday and find the page that listed either Java or IRC, then click on Join Chat; it worked for me. I was having the same problem you were. Look forward to seeing you in there.