I have been exploring and developing an application in Python for mission critical work in the commercial banking arena. 
Banks are way conservative in selecting new applications.
I need real proof of stability and others using. 
Have looked at the Python site but now I'm hoping this crowd can tell me more.
So far I don't have a development bank partner which I will need next stage, so I'm gathering proof and pitch info. All help and comments appreciated.
i know topic is rather old, but anyway.
if we talk about mission critical.
Python is widly used in Thales software provided with is hardware encryption solutions.
and in PayShield application for example, which i believe really mission critical.
Although Java is being used there more than Python.
Python in the enterprise: Pros and cons