For those of use turned off by PyQt's current license, Keep an eye on PySide:
"The PySide project provides LGPL-licensed Python bindings for the Qt cross-platform application and UI framework. PySide Qt bindings allow both free open source and proprietary software development and ultimately aim to support all of the platforms as Qt itself."
This project is backed by Nokia, and it seems like they are making good progress.
In any case, this news about pyqt is very welcome, I believe you can also use wxPython in a separate thread as well, you just have to "import wx" from the separate thread, and all subsequent wx calls have to be made from it as well.