SharePoint Ghost vs. Unghosted and custom master page

Question

If I make a custom master page, and put it in the file system where the standard master pages are, is the page ghosted or not?

Answer 1

You should use GhostableInLibrary in order to create a List Item in the Gallery list.

<Module Name="MyMasterPages" Url="_catalogs/masterpage" Path="MasterPages" RootWebOnly="TRUE"> 
    <File Url="MyMaster.master" Type="GhostableInLibrary">
        <Property Name="ContentType" Value="$Resources:cmscore,contenttype_masterpage_name;" /> 
        <Property Name="PublishingPreviewImage" Value="~SiteCollection/_catalogs/masterpage/$Resources:core,Culture;/Preview Images/MyMaster.png, ~SiteCollection/_catalogs/masterpage/$Resources:core,Culture;/Preview Images/MyMaster.png" /> 
        <Property Name="MasterPageDescription" Value="Provides the header, footer, and navigation used by my website" />
    </File>
</Module>

I'm not sure what you mean by where the standard master pages are. Your custom master page on the file system should not be in the GLOBAL or LAYOUTS directories, but inside of a custom feature. As an example, take a look at the PublishingLayouts feature (note, requires MOSS) and see how it provisions master pages.