yup.
one possible way to implement it is to export the current state of everything into a new skin. With all those implementations out in code.
* If there are changes to the CSS stylings, they go into the skins CSS file.
* If there are module template over-rides they go into the skin as skin file over-rides.
* If there are changes to the skins templates, they become current skin templates.
* and a button in the 'system check' to say if you have any over-rides active.
another one to add in for good measure would be to export any added custom Form Designer fields and package them with the skin too.
It would be useful, i agree. I'll beta test it for you.