After upgrading to Snow Leopard, I'm having trouble building my application.  It looks like py2app is building and copying over wxPython, but when I run from the buld app, it can't find wx.
I solved this by doing a clean Snow Leopard install, and installing python from Python.org, then the corresponding wxPython.  py2app I built from source.
py2app dropping wxpython (Snow Leopard)