Does anyone know what this thing is for?

Easy it mods the pads to make a LGA 771 cpu (Xeon) work in LGA 775 board. Basically they are very similar with just a couple pads that are different, it allows the right contacts to be made allowing a LGA 771 CPU to work in a LGA 775 board. The LGA 771 Xeons tend to have higher clock speeds for less money and also overclock really well. You also might have to mod the socket slightly to use this as the notches are in a different spot so you just get rid of them on the socket to allow the cpu to fit properly.