As a part of one of her projects, Lorna Mitchell had a need to deploy database patches as a part of her overall deployment process. Obviously, doing this manually every time can be a hassle so she came up with a script that does the work for her (based on a patch_history table).
My current project (BiteStats, a simple report of your google analytics data) uses a basic system where there are numbered patches, and a patch_history table with a row for every patch that was run, showing the version number and a timestamp. When I deploy the code to production, I have a script that runs automatically to apply the patches.
The script uses the number-based patch names (such as patch1.sql) and finds the latest ones that haven't been applied based on the highest values for the patch_number column in the database. This number is updated by the patches themselves when they're run to avoid any confusion in the script itself. She has it running as a part of her phing build process as a part of a Zend Framework application.