At Fanout, we are big fans of open source and open standards, and we are excited to be able to contribute our own projects back to the community!
Our software stack and cloud service provide a superior realtime solution, not just from a functional perspective, but also for risk management. If you ever want to transition away from the cloud and run the software on your own servers, you can. If you ever need to modify the source code to meet your needs, you can. You won't find this level of flexibility anywhere else.
Also, Fanout wouldn't exist without open source software components created by others, so we'd like to give a shout out to some great projects: ZeroMQ, Mongrel2, Tigase, Redis, MySQL, Django, Qt, Faye, and xmpp-ftw.