I tried to craft snow blocks by doing 2x2 with snowballs(like how you place planks to make a crafting table). It didn't work. So I tried a few other things, and couldn't find any that worked. On Single Player(and non-EMC multiplayer), i could craft a snow block out of 4 snowballs in a 2x2 shape. I only tested on Smp1, but I figured if it's on Smp1 it's probably on all of the servers.