Collabedit now has sidebar chat! There are still has a few minor quirks with it. I ran into some trouble with EditArea (the javascript text editor I'm using) because it requires browser focus in order to update the text. I've got my eye on Codemirror and some other alternatives though.

I've switched to using Tornado as the underlying web server. Tornado will enable me to use comet (aka "long polling", "server-push", "http-streaming", "bosh") technology. I haven't taken full advantage of that yet, but I will. Tornado also has a built in templating system, authentication, database helpers and a few other nice features.