The ISV.Config file is an xml file that allows menu items, menus, toolbar buttons and navbar items to be added to your instance of Dynamics CRM. After a fresh install of Dynamics CRM or an upgrade, export the ISV.Config file and save it as a reference. You’d think that as the instance has not been customized, that the ISV.Config file would be blank but what you find instead are working examples of all interface extension points.
The default Dynamics CRM 4 ISV.Config file: ISV.Config