Eskimos have 12 words in their language for "snow." I believe this has to do with the types and conditions of snow they live with. Your estimation regarding Zach's question about cleaning rugs in snow was absolutely right on. I have been doing this method, even with my room sized Bijar, for several years. I've even gotten Nathan Koets "permission" to clean my rugs this way.
My method is to wait until there is adequate snow to cover the ground, and until temperatures are below 25 degrees. Then, when there is a nice fresh snowfall of dry powdery snow, I roll up the rugs and put them outdoors overnight to "equalize" their temperature. Putting a room temperature rug onto snow would cause melting, followed by refreezing, causing ice to stick to the pile. You don't want that.
Once the rugs are "cold" I roll them out face up, just like in the house. I shovel some snow over them and let it sit for a while. Then I take a nice clean bristle broom and sweep the snow off, horizontal to lay of the pile. If there are dirty places, from Mary's sucker or something, I clean it off with a damp cloth.
The tough part is yet to come. One wants as much snow off the rug as possible. So, I use a stiff bristle brush to brush all the snow off the top and bottom of the rug as I roll it tightly. I brush, and roll, brush and roll, until the piece is rolled up. Then I carry it to the porch for a final brush, and take it in the house. The rugs are rarely even damp after this procedure and they really love it! Room sized rugs will likely require two people for the "brush, roll and carry" procedure. It is very very effective in removing all lint, hair, and surface dust. I do not recommend this method for a very dirty rug.