We're happy to announce that the new Pogoplug Series 4 plug computer has joined the ranks of our officially supported devices, complete with an updated U-Boot installation and a shiny new kernel that enables those USB 3.0 ports people have been itching to make good use of. The installation is also done in such a way that reverting back to stock functionality is dead simple, should you decide that a full Linux install isn't the right thing for you. Those instructions as well as information on controlling the LEDs are under the Advanced tab on the platform page.
A few notes on the installation are in order first, however; and these echo what is said on the device's platform page. There is no support for booting from SD/MMC or USB 3.0 due to U-Boot limitations. The storage device you use for the root filesystem must be in one of the top two ports, USB 2.0 or SATA. The dock on the top is compatible with Seagate's GoFlex line of portable hard drives, and that's what we suggest you look into for the best performance. It will only fit the slimmer versions that come in sizes up to 750GB. The 1 and 1.5TB models are almost twice as thick and won't fit in the space provided. Any other similar model by other manufacturers, or even a bare 2.5" drive would likely work well.
Our U-Boot is capable of recognizing a few different usage scenarios, depending on how you wish to handle your install. You can have both SATA and USB drives plugged into the top at boot, and U-Boot will figure out which has our operating system and adjust boot arguments accordingly so you should get a clean boot every time.
For those of you that like to push things further, the Series 4 is based on a Marvell chipset, which means there is a Marvell SATA controller lurking inside. This means that the SATA port is hot-swap and port-multiplier capable. If you have an external drive array enclosure, you could grab a male SATA to eSATA cable for a few bucks and link the whole rack into the plug. These chipsets also include hardware XOR offloading that is enabled by default, which means RAID 5 parity calculations don't take a chunk out of your CPU.
The Series 4 also has an Eject button on the back that we have enabled, but not tied into anything specific. In the stock firmware we assume this was there to trigger their software to safely unmount drives you had plugged in before yanking them. The button is a GPIO key, and the kernel will bind it to /dev/input/event0. You can see it working by cat'ing the device and pressing the button. There are different ways to interface with input events, and we'll leave that to the community to come up with the best uses for it.
Without further ado, have at it!
Arch Linux ARM on Pogoplug Series 4
Also, take a look at the notes at the bottom of the installation instructions in case you run into those situations.