In a recent virtual conference, I was asked about whether you can still ghost/unghost site pages when editing files in SharePoint Designer 2010. The short answer is yes you can, but the longer answer is as a site administrator you can actually manage this a bit more tightly in SharePoint 2010 (in effect disable it from occurring).
For those that are new to ghosting and unghosting of SharePoint site definition files, ghosted pages are pages whose content doesn’t reside in the content database (save as a row with a null value for Content); they reside on the actual file system disk. When site pages are customized, the page is unghosted and their content is then stored in the content database. The issue with unghosted pages is that site maintenance and performance can be affected (e.g. updating server or solution may be impacted or site caching may be affected). You can find more information on ghosted/unghosted pages here:
CodeGuru - http://www.codeguru.com/cpp/misc/misc/tools/article.php/c9581/
MSDN - http://msdn.microsoft.com/en-us/library/aa978512(office.14).aspx
In SharePoint Designer 2010, though, you have the option to have more control over how site pages are customized—thus disabling the ghosting process from occurring. To find this functionality, go to SharePoint 2010 Central Administration, and click General Settings, and then under the SharePoint Designer category click Configure SharePoint Designer settings—see figure below.
Under the Configure SharePoint Designer settings, you can check/uncheck a number of settings—one of which is the Allow Site Collection Administrators to Detach Pages from the Site Template option. If you uncheck this option, you are disabling the detachment of pages from the site definition—thus disabling ghosting from occurring.
What happens is that site collection administrators can now edit the site is Normal mode from SharePoint Designer; not the Advanced mode, which supports the ghosting/unghosting process.
Hope this answered the question from the virtual conference!
Hope to see you all next week at MIX and SharePoint Pro in Vegas!