Is it possible, on a linux machine configured for AD or LDAP logon, when the user logs on, to use that username and password to connect to a WPA enterprise wifi connection, which would then allow the AD/LDAP logon to go ahead?
Sort of, though it depends how your Linux machine is configured. If it allows cached credentials, then the intial login while the machine is not connected to the network (I am assuming this is the scenario) should be sucessful. Then the wireless can connect. After this you are logged into the PC, and the credentials are used to access domain resources. Not exactly what you asked, but effectively the same. If the AD credentials had expired, after logging on you would likely need to re-authenticate when accessing a domain resource.