Application pages that have not been edited and saved back to
SharePoint run from the file reference on the disk in the original
template location, these are GHOSTED pages - from a microsoft
document.

It seems that when the page is modified/edited using front page it
gets unghosted or disinherits itself from the site definition. Any
upgrades or patches made on the portal site definition will not have
any effect on the unghosted pages.

Does anyone have any information on this? Has anyone encountered this
situation? Can you ghost unghosted pages. I am looking for more
information on this topic.