Once upon a time, a Marvell developed a product called the Sheevaplug to drum up interest for their "Kirkwood" ARM-compatible CPU line. This was a complete linux system hidden in a wall wart, whose design they gave away as a reference. This led to a number of Sheevaplug-based devices hitting the market, including the PogoPlug, a line of cheap NAS devices which are all based on the Sheevaplug design with various single-core Marvell CPUs. They are now discontinuing not only that line but also the service for the same, so the devices are cheaper than ever before right now, and this is a great time to pick one up — I got one for $13.
I wrote an earlier article on installing Debian on the V4 pogoplug, and fairly little has changed since then, but it still seemed worth going over again in case anyone was wondering whether the "new", final edition of the pogoplug which is readily available for little money is the same as the prior version. In fact, the prior version of the hardware was sold under two model numbers; the POGO-V4-A1-01 had a blue logo on the case front and was sold as the "PogoPlug Mobile", while the POGO-V4-A3-01 had a purple logo and was simply sold as the "PogoPlug". As stated previously, the new model's name is the PogoPlug Office, and its number is POGO-V4-A3-02. However, there is literally no discernible difference between the -01 and the -02. Possibly the model number was used to signify that the device came with different software loaded on it from the factory.
The change that has led to the recent unpopularity of the device is that while it used to be possible to "hack" the device to run a full Linux distribution simply by asking Cloud Engines to unlock ssh on the device for you, and then downloading and running a script, they took that functionality away. This does not make the task impossible, but it does complicate things slightly. It is now necessary to solder wires or a connector to the serial pads on the board in order to gain access. Having done this, the user connects a 3.3 volt serial adapter at 115kbps, and is rewarded with a root prompt.
At that point, you have a couple of options. You can use the old-school installer script to install Debian on the system. You can try bodhi's new install script instead, but I can't tell you how well that works because I didn't try it myself. Or you can manually prep an SD card, and then unpack the debian rootfs and latest kernel to the card, as well as the updated u-boot. First, partition your sd card as one big ext4 partition named "rootfs" (this u-boot has ext4 support, and the default fstab uses disklabel) and then unpack the rootfs into its root. Then unpack the latest kernel tarball into the "boot" directory, you will mess with that after booting. Unpack the u-boot archive somewhere, probably into the "root" directory. And finally, unpack the flashing tools into usr/local/bin.
Once you've done that, follow the flashing instructions for u-boot, adjusting the paths as necessary to reflect where you unpacked files. Pay special attention to preserving the mtdparts environment variable if you care about being able to boot into the original system. If you forget to save the variables, you can at least get the original ethernet hardware address off the bottom of the unit. At this point you should be able to reboot into Debian, apt-get autoremove to clean up messes, and then install the new kernel. Then "Generate the uImage and uInitrd" and reboot again to enjoy your fresh new Pogo-Debian system.