Centrifuge: Real-Time Web App Message Broadcasting
Centrifuge looks like some pretty awesome messaging technology that uses Tornado, ZeroMQ and Redis.
The main goal of Centrifuge is the same as in Pusher or Pubnub services. The main difference is that Centrifuge is open-source and requires installation (it is worth noting that installation is rather simple).
-- GitHub Page
To get a fell for the simplicity of Centrifuge, check out the GitHub page's architectural diagram and admin interface image.