I'v created a project db-dump on code.google.com, you can visit it at:
http://code.google.com/p/db-dump/

And db_dump.py is used for dump and restore database of Django. And it
can also support some simple situations for Model changes, so it can
also be used in importing data after the migration of Model.

So if you like it or want to try it, you can download it from
http://db-dump.googlecode.com/files/db_dump2.1.zip

And if you have any idea about it just write a issue or send me an
email, I'll try my best to change it.

If you want to run it, just extract it to project directory, you
should put it with the settings.py together, and run it according to
the document of the project site.

Hope you like it.
-- 
I like python!
UliPad <>: http://code.google.com/p/ulipad/
My Blog: http://www.donews.net/limodou