Manhattan's very first Dairy Queen finally opens to the public at 10 a.m. today and, predictably, it's already drawn a crowd. The first 50 customers today get a gift card for one free Blizzard a month for a year, which means that the line started forming well before 7 a.m. The first 200 people also get a "signature DQ-NY t-shirt," which may or may not be some consolation to those who didn't get there by the crack of dawn. In any case, there are Blizzards for everyone, plus burgers, Buster Bars, Orange Juliuses, and two floors (complete with couches) of DQ Grill & Chill to eat it in. And students take note: DQ is wooing what are sure to be its best customers by offering a 15 percent discount to anyone with school ID today.