Migrating changes from development to production is particularly tricky in Drupal due to a large amount of configuration settings being stored within the database. Attendees of Drupalcon 2008 made it clear that this is a particularly annoying problem. I attended the Development / Test / Production Environments panel to learn about how the big guys (including Drupal.org itself) manage deploying their sites from one working space to the next. We were disappointed to discover that even the big guys are currently writing down all the steps to upgrade and simply performing them on the production server.
This method poses several problems due to the Human Element being involved in the entire process.