Source, found through the most helpful google…
What about my Python scripts?
When a script uses calls that are part of the Blender Python Script Interpreter, the interpreted program, to Blender, is just data; you can run it any way you like, and there are no requirements about licensing that data to anyone.
The Blender Python Script Language is defined here:
This only applies to the Blender Python API calls. Scripts still have to follow the licenses of other code, bindings or libraries that they might use.
If you link a Blender Python script to other libraries, plug-ins or programs, the GPL license defines they form a single program, and that the terms of the GPL must be followed for all components when this case gets distributed.
The bottom line is that we consider everything you can create in Blender as ‘data’, including Blender scripts. But when you extend Blender with “other facilities” you have to follow the regulations of the GPL.
Author publishes a Blender script mixed with own code, under own license.
Not OK is:
Author publishes a Blender script, calling a compiled C library with own code, both under own license.
Author publishes a Blender script, that calls other scripts with own code, under own license.
Not OK is:
Author publishes a Blender binary with own scripts, bundled under own license.
The divider is “If the script runs in the Blender Interpretor”. When the script calls code not running in the Blender Interpretor you are making bindings to other facilities, and the regular GNU GPL rules apply.
Of course this only applies if you link your script to a gpl’d (or similar) licensed lib, if you linked to a BSD’d library for example then you would have to abide by the terms of the BSD license which has no requirement of releasing your changes.
Oh, and the creator always ‘owns’ their work, what the GPL provides is the means to distribute the ‘owned’ work of others.
In other words you can do whatever you want with gpl’d code but if you wish to distribute it to others then you must abide by the terms of the GPL which is usually that you must also provide your changes to their ‘owned’ work but you retain copyright to your changes – well, subject to copyright law on ‘derivative works’ which means you may or may not actually own the fruits of your labor…