Is there a Python module for the translation of texts from one human language to another? I'm planning to work with texts that are to be pre and post processed with Python scripts.
What other Python-integrated approaches can be used?
What to use depends on what you want to translate.

Texts that are a part of your application, like UI etc. Then use gettext directly, or zope.i18n, which wraps gettext so it's easier to use.
Arbitrary texts: The Google Translation API is the thing for you.
"Content", ie things that the user of the application will modify and translate: Well... nothing, really. You have to implement that yourself.

On your description, it sounds like you are after #2.
Translating human languages in Python