"To create realistic precipitation effects, Bethesda originally tried to use shaders and adjust their opacity and rim lighting, but once the artists built the models and populated the world the snow appeared to fall too evenly. To work around this problem, they built a new precipitation system that allows artists to define how much snow will hit particular objects. The program scans the geography, then calculates where the snow should fall to make sure it accumulates properly on the trees, rocks, and bushes."You're wrong. Snow will not be a shader.
Well, probably nothing will make you think otherwise, but it will still be a shader. These articles very poorly relay information. But as made apparent by the several high-res screens we now have, snow is a 2D pixel-shaded effect, laid over top of the surface geometry, based on the surface normals. It's exactly like the snow as seen in Crysis and Crysis Warhead, but inferior in many ways. There are strange striped artifacts on the snow. It exceeds the Crysis snow in one way, and that's that it has an artist-directed component which makes the snow appear not so even. In Crysis basically everything looked white.
"scans the geography" = has the world space normals, including normal maps
"calculates where the snow should fall" = limits the possible areas for snow to be placed based on these world space normals. The surfaces that point directly "up" will collect the most, and angles less than "up" will receive less and less snow.
"tried to use shaders AND adjust their opacity and rim lighting" = they at one point had more simple shaders that didn't take into account the surface normals. They also didn't have this artist-directed component, which probably equates to "snow density maps" in game, which prevent snow from ever showing in certain areas. Doesn't mean they don't place the snow with a shader now.
Don't rely on people who know nothing about graphics technology to relay it to you correctly. They took many an artistic license in those articles. I know with absolute certainty the methods they're using on Skyrim just from the screenshots.
What we haven't seen, though, is how snow will appear on terrain. I'm hoping they try a static, fake volumetric effect ala Uncharted 2 or Lost Planet 2. With some snow animation at your feet. This will go a long way with making snow seem volumetric when it's really not.