The same brand that makes underwear for Michael Jordan has created a "super suit" that will exceed down's warmth and eliminate its puffiness.  To test the Hanesbrands' suit, they are sending mountaineer Jamie Clarke on an expedition to Mt. Everest.

"The Champion Supersuit insulation is just 3 millimeters thick, compared with a typical goose-down jacket thickness of 40 millimeters, and uses a nanotechnology insulation layer and a proprietary radiant warmth system. The result is a breakthrough ultrathin cold-weather garment that is no thicker than a typical computer mouse pad but provides equal insulating properties, greater mobility, and superior wind resistance than typical extreme weather gear." - Hanes Press Release

The suit makes 5 key improvements to the current puffy coat:  No SEAM overlaps with another, the BASE LAYER is knit to cater to the body's needs, insulation with AEROGEL , an INNER SOCK that absorbs, stores, and returns heat to the body, and a thin layer of Radiant Foil is placed inside the insulation to capture the body's heat and reflect it back to the climber.

Today a jacket with similar technology would cost you 2K, but Hanes hopes to have a more affordable version on the market by 2011.  See the full specs at Fast Company.