Jim,
If you have access to the Image Server Manager, you can find all the necessary information for all the published image services (state, number of service providers, path to ISCdef file, etc.)
You can access the manager from Start --> All Programs --> ArcGIS --> ImageServer from the machine running Image Server.
Additionally, you can get the list of published services from the from the ImageServer.Services XML file, most likely located at C:\Documents and Settings\All Users\Application Data\ESRI\Image Server\Server.
Hope that helps.