After I dropped my bike on an icy patch of packed snow a few weeks ago, I doubt I'll every try to ride on snow with two wheels again.
If you want to see how to do it properly, check out the Everyday Riding blog. Two wheels or three, he's riding around Minneapolis year-round and taking video. In winter, he's normally out on his Ural (with sidecar) but yesterday he was out in deep snow on a 2-wheeled scooter at 13 degrees below zero!
I'm in awe.