I tried to created an account to see it live at https://www.fossil-scm.org/home/chat but it appears they have /chat locked down to authorized accounts.
(Regardless of what others might be saying in this thread, I think this functionality is great. It reinforces the centralization of your dev related work. Plus, presumably they are using SQLite on the backend - so /chat might result in now additional functionality being added to SQLite that might also be beneficiary e.g. removing blocking on writes, etc)