1.1 Users, remember this number:
Those are the digits of the world that will make all your snowy mountainy goodness come true. From your spawn, just turn west and start walking. And walking. And some more walking. It's like the snow biome and the mountain biome got together and had quintuplets.
Skeptical? Feast your eyes on these:
View from the spawn:
View further in, where things get higher:
Want a snow-covered mountain range?
Just type 8300352857188354047 (or copy/paste) into the seed box and go have fun!
(Only applied to 1.1. No pumpkins were spotted during exploration, but that doesn't mean they aren't around)