I can see the serial numbers on the 2K3 server.  How can I get the
serial-numbers from AIX ?

Zoltan,

Try lscfg -vl.

$ lscfg -vl rmt0
  DEVICE            LOCATION          DESCRIPTION

  rmt0              10-58-00-4,0      IBM 3590 Tape Drive and Medium
                                      Changer

        Manufacturer................IBM
        Machine Type and Model......03590E1A
        Serial Number...............0000000C2646
        Device Specific.(FW)........E35A
        Loadable Microcode Level....A0B00E26


$ lscfg -vl rmt5
  rmt5             P2-I5/Q1-W2001006045170A1A-L2E000000000000  IBM 3580
Ultrium Tape Drive (FCP)

        Manufacturer................IBM
        Machine Type and Model......ULT3580-TD2
        Serial Number...............1110089774
        Device Specific.(FW)........38D0