Question has been asked before about how to synchronize files as well as the database between two Wordpress installations.
For the database level, the answer is usually to basically dump one database and insert it onto another server. The problem with this is that you end up losing any changes that have potentially been made on the prod server. For instance, usage metrics, comments, etc...
With this in mind, I was starting to wonder whether the it would be possible to extend the Wordpress ORM so that you can generate deltas and then inject those into the prod site.
Has anyone tried this, looking into it, or have any ideas or comments ?