New Belgium Brewing Company: La Folie

Official description from the brewery:
La Folie spends one to three years in big oak barrels known as foeders. And when the beer finally hits the glass, La Folie is sharp and sour, full of green apple, cherry, and plum-skin notes. Pouring a deep mahogany, the mouthfeel will get you puckering while the smooth finish will get you smiling. Not for the timid, La Folie is a sour delight that will turn your tongue on its head.