I've found a SAN device that would do both virtual tape libraries in
  various formats as well as tape output.  Any device that's "iscsi
  aware" can see this unit on the network and move data to either the
  tape library or an actual tape.  It would really be neat if Amanda
  could write to the virtual disk and the tape.

  My problem is the "iscsi aware" factor.  As I understand this, Free
  BSD's iscusi driver or interface is still in the development or beta
  stage.

I think the right way is to have the underlying OS provide an iSCSI
client so that the SAN appears as a disk/tape/whatever.  It seems messy
to put this into amanda.