So what's this I hear about scene referencing in messiah?
Well the general gist of it is that you have a master rig scene, and an animator scene and the changes you make in your master scene are reflected in your animator's scenes.

Say what?
I said, the changes you make in your master scene are reflected in you animator's scenes!

Oh, how do I do that then?
1. Create your Master Rig File.
2. Save the scene and save also a seperate duplicate of the scene for the animator.
3. Hit load scene and select the animator's duplicate scene.
4. Select 'merge scene' and save the animators scene in the animator's production folder.
5. Now, whenever you change the master rig file and save it (ctrl+s) messiah will automatically give it a 'referenced scene version' which is equal to the current version + 1.
6. When the animator loads his scene, if the master rig scene has changed, he will be told what the current version of his master rig is and what the latest updated version of the rig is and asked whether or not he wishes to load the latest scene.
7. If the animator chooses to load the latest rig scene file, all the expressions, items and effects etc that belong to the master scene file will be loaded in assuming that they are different from the ones that are already in his scene, and all the basic parameters will be updated to the rig files. The animation the animator has done so far is kept intact.
8. If the animator requires more changes to the rig, you can simply update the scene file and rinse and repeat steps 5 to 7.

What's the problems with scene referencing?
You have to keep a close eye on the fact that the changes you make to a rig could change things that they have done in the animation. If the animation won't be affected you can usually safely update to the new version of the rig. If you've done something that is so different that it will change the motion identity of the character in the animation, you would typically do well to advise your animators to stop updating that animation file unless the new functionality in the rig outweighs the problems with updating the motion in the file. A good habit in production might be to back up their scene file before they update to the new master rig file, just so you don't break anything.

Is there somewhere I can look at how cool this is in action?
You can use your eyes to view this demonstration on your computer screen using the power of the interweb: http://www.usefulslug.com/messiah4/Referencing.mov