So, it turns out we were way off in our predictions for where Diner En Blanc might take place. If you haven’t already heard, the flash-mob dinner went down last night at the fountain at Logan Circle near 18th Street and the Benjamin Franklin Parkway. White-garbed and fabulous, the 1,300 or so who turned out for it sipped, supped and elegantly partied down as passersby casually gawked at the spectacle unfolding in front of them. Grub spotted Le Bec Fin owner Nicholas Fanucci and his wife, Franklin Mortgage and Lemon Hill owner Mike Welsh, and London Grill’s Terry Berch all repping Philly’s hospitality set. By night’s end, hundreds doffed their white shoes and collectively took a dip in the fountain, giving way to what might have been the city’s largest ever wet t-shirt contest.