myCornell leverages Reference groups from Active Directory in addition to legacy permits and can be configured to be aware of any AD group. By default Announcements is made aware of all groups myCornell is aware of. The myCornell implementation uses PAGS (Person Attribute Group Store) as the primary means of defining groups. The attached spreadsheet is current list of the groups myCornell is configured for as well as a list of the pushed tabs and the published portlets.
If a portal user is not seeing a tab or portlet they believe they should see, the spreadsheet can be used to determine what groups a particular tab gets pushed to. If the user is not in a reference group (all prefixed with rg.), then the user will need to pursue with HR getting placed into the correct reference group. If the group is a legacy permit, you can look up the updater or admin group for the permit in the ActiveRoles server. If the groups is a local AD group, the list of local AD ou admins is available here.