Just as night watchmen are constrained by duty to make their rounds, so are writers about wine. Sometimes the rounds are seasonal. Beaujolais Nouveau, for example, is released every year on the third Thursday of November at 12:01 a.m., just a few weeks after the September harvest. Gamay, the grape that makes Beaujolais, can be fresh, floral and ruby-like in this nymphet incarnation.