I think this is solution of your problem:
http://code.google.com/p/freebsd-pyside/wiki/Functionality#Troubleshooting
bq. problem
from PySide.QtGui import *
ImportError: /usr/local/lib/python2.7/site-packages/PySide/QtGui.so: Undefined symbol "_ZN9QGtkStyle11qt_metacastEPKc"
solution
The current solution is to rebuild py-gui after changing your /etc/make.conf to include:
QT4_OPTIONS += QGTKSTYLE