I have a fresh install (started with a wiped drive) of Snow Leopard with the developer tools installed during the Snow Leopard installation.
I then installed Python
Solved in 2 steps:
Step 1: Uninstalled and Installed Xcode, suggested here: http://binarylionstudios.com/blog/2011/01/30/error-stdarg.h-no-such-file-or-directory/
to remove Xcode properlly follow this answer: How to fully remove Xcode 4
sudo /Developer/Library/uninstall-devtools --mode=all
use the install Xcode.app after you restart your mac
Step 2: after xcode was reinstalled, the installation failed
unable to execute gcc-4.2: No such file or directory PIL
to resolve that i followed this post: http://aravir-rose.blogspot.com/2011/12/installing-python-27s-imaging-library.html
Good luck!