Supposedly this is a chat server to run as a login shell for users ssh-ing to a particular box.
Apparently, unlike a e.g. Jabber server, your whole interaction, including the typing of your messages, happens in the remote terminal session. Probably this is perfectly fine for chatting inside your LAN, but probably not best if your connectivity is limited or just has a high latency (imagine a ping from Iceland to New Zealand).
It seems that long-term history is not supported yet.
Still this thing must be easier to set up than IRC over TLS.
Mosh doesn't really impact real latency, just perceived latency by buffering the screen (and ironically, is slower on good connections than regular ssh).
The only change request I'd suggest is using IRC as the backend for that chat (i.e. make the ssh chat daemon act as an IRC client to a local IRC instance instead of using the Server.Broadcast mechanism) - it would give a big boost in functionality with not a lot of additional effort.
This exposes your public key through /whois <username>. In order to protect that along with hiding your system's default username, join with "ssh -o PubkeyAuthentication=no <username>@chat.shazow.net"