PyQT Licensing and plugins/scripting

[Fabio]

Hi all,
I'm about to write an application, and I'd like to use PyQt, but before
choosing this toolkit I would like to clarify some particular licensing
issues; if some user has already touched these, I would like to hear from
his experiences.

This app should be cross-platform, so, given qt licensing policies, I would
buy a commercial PyQt license and a commercial Qt license.

Could I license the application under the GPL for Gnu/Linux and under a
commercial license for Windows and Mac OS X? If this is possible, I guess
that contributions to the GPLed version could not be incorporated in the
commercial version, but this would not be a big problem.

The main issue with licensing is that I would like to give users of the
application a scripting framework (for macros and the like), and eventually
a plugin framework; PyQT redistribution policy states that if an user can
get in touch with PyQT directly it should have a commercial license itself;
how does this apply to those who want to develop commercial PyQT
applications with a plugin/scripting framework?

Thanks,
Fabio