It's a board that does power distribution but offers ports that don't backfeed into the rest of the device. Some cheap USB devices (and some expensive commercial devices) will supply power through their input port if power comes from another source, like a USB device that's plugged into it. This way, the offending device doesn't try to power the rest of the system or fight with other power on the bus. The Potato name came from someone I used to work with watching me lay out it's predecessor, and said something along the lines of how that was a potato of a board for all it did. The name stuck.