Lots of builders are using stainless tubes from Columbus, Reynolds, and KVA. At this year's NAHBS there were stainless bikes on display from Naked, Dave Anderson, Dave Wages (Ellis Cycles), Cinelli, and several others. I also know Carl Strong and Bob Brown build in stainless. As squirtdad says, I've got a stainless Waterford RS-22. These bikes are light and strong, and because they're corrosion resistant there's no need for paint (with its additional weight) to protect the bare steel. My 61cm frame weighs 1650g.