A new feature I'm working on is exposing the GameObjectClass and derived types. That most likely doesn't mean a lot, so I will explain. Every GameObject in the game (ships, stations, terrain objects and so on) is of a particular class. That class defines the way that every ship of that type behaves and is built from the ODF file.
MMM already allows you to change properties of individual ships via the Entity and derived classes. This is all you need to change a specific ship. However suppose you wanted to upgrade a ship class - say the Akira class. You can now actually edit the definition of the Akira class in script to give it the upgrade. So you could set the maximum shields of the Akira class and all Akira class ships built after that point will be affected.
You will be able to access the class of an Entity using the class property, or browse the different classes that currently exist. Changes to classes do not persist beyond the lifetime of the mission - when you go back to the menu all changes are lost, so you don't need to worry about affecting other missions with your changes.