Development:
Kubuntu 7.04 (Feisty)
python 2.5.1
Gui toolkit: wxPython 2.8
Editor: Kate.

Distributing with py2exe:
Windows XP (in vm)
Python 2.5
Gui toolkit: wxPython 2.8
editor: notepad++, Idle

ps: it's nice to see so much variation in this thread.