Load local settings

If you have a production, staging, testing and development environment, you might want to have a global checked in (in your version control system) settings.py for production + a local settings.py to override various settings (like database connection).

It's also good for development, since developers don't - by incident - commit to the production settings.py, since they can use their local settings, that should be ignored (.cvsignore, .svnignore or similar).