It's a "gnocchi board". Used along with that wooden dowel to slide the gnocchi down the board and create the ridges on the gnocchi. Completely unnecessary, but my girlfriend has always REALLY WANTED to use one to make gnocchi for some reason.
Those gnocchi were very large. Much larger than what you'd probably normally expect, but they were so friggin' good fresh out of the pot. I'd recommend trying to make them, it really was simple:
* Boil or bake potatoes until they are soft
* Mash potatoes up really well and let cool
* Add flour and roll into gnocchi sized logs (they say to use just a little bit less flour than you have mashed potatoes. Just keep adding flour until you have a dough you can work with)
* Cut into bit sized gnocchi pieces
* Boil until the gnocchi starts to float. When 5 or so pieces start to float, take them all out.
* Add sauce and enjoy!