NBC NEWS star Katie Couric has taken Hollywood and late night TV by storm, overnight NIELSEN ratings show, after the TODAY show host tried her hand at TONIGHT duties -- with stunning success! Last night's 7.4 rating/18 share for Couric from Burbank is near record-levels for late night, with an audience size gauged at nearly double over last Monday night's standard Jay Leno run on NBC. Meanwhile, on the other side of the flip, Jay Leno's hosting of Couric's TODAY on Monday morning maintained audience levels from last week, with a 5.9 rating/18 share. MORE "Couric may, in fact, be...