FWIW, I'm using essentially the same hardware in a slightly different package (purchased
here), but, lsmod has the same signature:
$ lsusb
Bus 001 Device 005: ID 0930:a002 Toshiba Corp.
Bus 001 Device 004: ID 067b:2303 Prolific Technology, Inc. PL2303 Serial Port
Bus 001 Device 003: ID 067b:2303 Prolific Technology, Inc. PL2303 Serial Port
Bus 001 Device 002: ID 2001:f103 D-Link Corp. [hex]
Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub
$
Here is my lsmod:
$ lsmod
Module Size Used by
nfsd 261016 9
exportfs 4364 1 nfsd
dm_crypt 14084 0
dm_mod 59152 1 dm_crypt
pl2303 18720 1
usbserial 32856 3 pl2303
$
(Note the pl2302 module!) I'm using the 2.6.30-rc6 kernel that came with the
Alpha 6 Sheeva Installer. When I plug in one of these devices, it is correctly identified, usbserial and pl2303 automatically load, and the /dev/ttyUSB* devices are automatically created. Prior to loading this kernel, I observed that the original OS that came with my Plug did not know how to deal with these devices. It looks to me, from the FATAL you posted, that you are using something akin to the initial load -- 2.6.22.18. I can't tell you how to make these devices work with that load, but I believe if you upgrade using the Alpha-6 installer, it will resolve your USB-to-serial problem.
Good luck!