If you are a developer using Python for any purposes (warning: you could be using without knowing), do take heed.
As discussed in my previous post, upgrading to Mountain Lion will cause many of Python packages not to work. I have found out that /Library/Python/2.7/site-packages/ was cleared! The site-packages directory stores all the third party libraries that you have installed eg. virtualenv, django, pip, mysql, etc..
I have yet to understand the reason for Apple doing that warehouse clearance..
However, a tip for you:
If you are upgrading to Mountain Lion, backup /Library/Python/2.7/site-packages/ to Desktop first. After upgrading, you can copy site-packages back.
I also encountered missing path to mysql and mysql_config commands. Somehow PATH got altered. Here’s the fix: