I believe that Ghost places some sort of marker on the hard disk the first time it is run, so consequently I would be surprised if this could not be audited in some way.
If you convert to another platform then you will need to create a new image for deployment in the format required by your new platform. If that happens to be SCCM, then the image will be a WIM file. You could, of course, deploy a Ghost image to a hard disk and then immediately create a new image with the tools from your new platform. I don't know whether there will be any identifiable Ghost content within the images, so if you are concerned about licensing issues, it would be safest to bite the bullet and recreate your images for the new environment.