For those finding this thread from Google as I did, I resolved this in my case after heeding the advice of the author of the MySQLdb lib:
http://mysql-python.blogspot.com/2008/03/i-am-not-dead.html
In short, make sure your MySQL installation is 32-bit if you're using a 32-bit Python installation (like stock OS X). So to summarize, a working setup for me on Leopard:
* Install pkg version of MySQL, x86 and NOT x86_64
* Download 1.22 tarball of mysql-python
* Comment out uint lines from _mysql.c as suggested in this thread (lines 37-39).
* Install as an egg with `easy_install ./MySQL-python-1.22`
'import MySQLdb' is now happy in a Python console with no errors or warnings. Hope this is helpful to others!