Mine is(was?) in Python with an XMPP lib. I hadn't gotten around to solving the async problem yet, so I'll probably just jump to Hubot.

I wrote one in Python (Twisted) a while back, but with any of these things: better for more to maintain it than just me.

Mine was XMPP but also supported other async protocols (Redis PubSub, Spread).

too late for me :(

http://github.com/grifo/florinda

Looking at it, it's very possible that hubot's scripts are interchangeable with ours with a small translation layer.