"Next piece of wow: we will be open sourcing all of the Gitter"

The Gitlab folks really know how to do it. It is of course the rational approach to it, but still, that's a bold move.

Do we know what protocol Gitter runs on top of?

Gitter uses a proprietary websocket protocol built on top of the Bayeux protocol: https://docs.cometd.org/current/reference/

More details can be found on the developer site: https://developer.gitter.im/docs/faye-endpoint

We also have an open-source IRC bridge: https://github.com/gitterHQ/irc-bridge