One has to feel a little sorry for Knut, Berlin's world-famous polar bear. During the summer, the city tends to be hot and humid for long stretches, way too warm certainly for his white fur coat. Consequently, Knut spends much of his time swimming and rolling in the dirt, making him look more like the brown bears in the enclosure next door than a displaced resident of the Arctic. This week, though, has seen the German capital covered in a -- for Berlin -- generous blanket of snow. Knut, needless to say, is in ursine heaven.