Managing Environment Specific Config Files?

byrnereese asks: "It seems that every organization I have worked for has been plagued with the same problem: 'how do you effectively manage multiple environment configurations for the various development, staging and production environments that exist.' For example, each application at our company requires a different set of database credentials for each environment we deploy it to. For a long time we have maintained different config files for each environment and checked them into our SCCS; but that has proved incredibly error prone because a different build is required for each environment. Each company I have worked for utilizes a different systemology to make config file management a little easier, but none of them have stumbled upon anything that is any less error prone, or any easier to manage than any other solution to choose from. So I am curious, how does your company manage environment specific application configuration? And what does your change management process for these configurations look like?"