Hi Torsten, this is Jonathan Hosmer, creator of Python for iOS. Unfortunately, Apple will not allow me to register the ".py" extension for use with the "Open In" feature. In the last update (v1.3.1) I did register to be a target for .py "Open In" but when I submitted it to Apple for review they rejected the update and said that it violated one of their policies that does not allow importing "executable" code into an app that can run that code. If/when Apple changes this policy I will include this feature into the very next update though.
Customer support service by UserEcho