Good point. I hope it's in. Given that JADE is suposed to generate its own world, it would be strange if there were no snow.
I sure hope to see tundras and taiga, frozen rivers (with bridges akin to those created by blasting ice spells at the water), slippery slopes, snow covered hills and forests. Frozen land, and snowdrifts that slow you down, like the swamp and rugged terrain. Snow caverns... etc. Got carried away for a sec.
As to the skills, I think Ranger's class powers will be more useful this way, same for Woodsman. Perhaps its usefulness should be expanded to aid in crossing other difficult terrain, or maybe Survival should also help here.
Oh, and why limit ourselves to snow only, Deserts should be in as well. Sand deserts, rock deserts, sandstorms, quicksands.