Well, we already have the SQL code stored inside the database so it can be deployed along with database changes to the server.  Maybe we should also make it possible to store and distribute application code to the database at the same time.  Then when the application connects, it pulls and implements any changes as they are required, similar to Windows Update.  Many commercial applications already check for new versions and advise us when available.  Then you simply advise users ahead of time that changes will be available and/or required at a certain point so they can plan for the update time.