Staredit Network

And it can be done without having to type in the topic's name or registering a topic, right? Otherwise its the same thing as Gabbly, where you have to put in the address of the topic you want to talk about.

It can be done automatically. If I didn't want you to be allowed to moderate/style your shoutbox, it wouldn't need a password and thus you'd just click "Register Shoutbox" and it would create it. When the thread is created, it would do something similar to what happens when you click "Register".

Oh, awesome. Then yeah, we should go with that over Gabbly. Plus, that can be done in-site, whereas Gabbly is still an off-site chat provider that we can't control.

Okay my mind has been changed. I vote for the tabbed shoutbox idea.

Ditto. As least, the in-house part.

Realize though that the purpose I'm trying to get at with having thread chats is so that someone can enter a thread, see someone else, and begin chatting with them directly, using the thread itself to set the topic and context.

Posts are typically something you have to commit to, whereas chat messages you can make with abandon. Chats are good for streaming information between specific parties, whereas posts are best for self-contained packs of information that lose context when streamed, and are addressed generally to a non-specific audience.