Here is the scenario.  We have to maintain a bunch of production web applications, most of which use Zend Framework.  When we have created a new version of the application, we need to deploy it to production in as simple of a way as possible.  We have automated the file version of this by using Phing to export the tag out of SVN, copy old config files, set write permissions in the correct place, etc.  However, the database manipulation has happened manually and we are looking for strategies on how to automate this.

We came up with an idea to write a custom migration library which will execute php and sql files, but it seems like a problem that has to be solved better by someone else.  Anyone have any tips?  Anecdotes?  Strategies?  Anything to help us get going in the right direction would be much appreciated.  I'd even buy someone a beer or two