Found this in a blog:
This is one poor system of WordPress. There is no template system. Actually there is a template system but not the template system like MovableType. If you modify your template that means *forever*. There is no *save* feature like in MovableType where you can save your templates in your database before applying them (or publishing/rebuilding).
Well, this is FREE software so we are FREE to modify the code to suit our needs. *Donâ€™t faint* you will see this feature in WordPress the next few days.