I am migrating my dev environment to 10.8, however I am having issues with pip.
Specifically, I\'m using a virtualenvs/virtualwrapper but cannot pip install ps
This probably happens because you did not re-install the Command Line Tools after upgrading.
Usually XCode should be upgraded to the latest version (4.4) (I believe when I updated to 10.8 I also updated a whole bunch of other applications, including XCode). After the update you need to re-install the Command Line Tools. This can now be done via a setting in XCode:
Go to "Preferences -> Downloads" and install "Command Line Tools".
Now you should have no more problems when installing packages that need to be compiled.