I looked at the source of samba 2.2.8a and 3.0rc1, both fill the
job-originating-host attribute with get_remote_machine_name(). 

So the orininating-host attribute contains the netbios name. Better 
would be if the originating host attribute contained the dnsname or at least the
ip address of the remote host.

I already programmed a little patch and sent it to the mailinglist, which uses 

       clientname = client_name();
       if (strcmp(clientname, "UNKNOWN") == 0) {
               clientname = client_addr();
       }

to fill in the originating host attribute.

Additional idea:
To have the netbios name somewhere in the cups attributes you could use
an attribute like samba-originating-netbios-host.