If the path for your mysql.sock does not correspond to the default tmp/mysql.sock you will recive the following error in osx.
File "/Library/Python/2.5/site-packages/MySQL_python-1.2.2-py2.5-macosx-10.5-i386.egg/MySQLdb/connections.py", line 170, in __init__
_mysql_exceptions.OperationalError: (2002, "Can't connect to local MySQL server through socket '/tmp/mysql.sock' (2)")
To correct this, find the real path for your mysql.sock (mine was var/mysql/mysql.sock) and then add the following param (under the mysql related params).
DATABASE_HOST = '/var/mysql/mysql.sock'
That should do the trick!