I've got a Pogoplug model Pogo-v4-a1-05. I've converted one of these to a file server in the past, when it was easily done: just go to the pogoplug website and enable SSH on the device and start uploading the files.
Its now more complicated and I had to solder cables to the serial console. That's all working well, and in picoterm I get the following for "printenv":
Soc: 88F6192 A1 (DDR2)
CPU running @ 800Mhz L2 running @ 400Mhz
SysClock = 200Mhz , TClock = 166Mhz
$this->bbcode_second_pass_quote('', 'C')E>> printenv
baudrate=115200
loads_echo=0
rootpath=/mnt/ARM_FS/
netmask=255.255.0.0
run_diag=yes
CASset=min
MALLOC_len=1
ethprime=egiga0
load_nand=nboot 0x800000 0 0x200000
load_nand2=nboot 0x800000 0 0x500000
boot=bootm 0x800000
boot_nand=run load_nand boot || run load_nand2 boot
ethmtu=1500
usb0Mode=host
nandEcc=1bit
ethact=egiga0
ethaddr=00:25:31:03:e2:b8
cesvcid=JYN24UBY4GGCM39XM2GZY2DUU2
ceboardver=PPV4A1
ipaddr=192.168.58.233
serverip=192.168.58.188
bootcmd=run boot_nand
bootargs=root=ubi0:rootfs ubi.mtd=2,512 rootfstype=ubifs console=ttyS0,115200 elevator=cfq mac_adr=0x00,0x25,0x31,0xAA,0xBB,0xCC mem=128 poweroutage=yes
stdin=serial
stdout=serial
stderr=serial
mainlineLinux=no
enaMonExt=no
enaCpuStream=no
enaWrAllo=no
pexMode=RC
disL2Cache=no
setL2CacheWT=yes
disL2Prefetch=yes
enaICPref=yes
enaDCPref=yes
sata_dma_mode=yes
netbsd_en=no
vxworks_en=no
bootdelay=1
disaMvPnp=no
hddPowerCtrl=no
pcieTune=no
Environment size: 908/131068 bytes
CE>>