Only one week back in the US, and already Giuseppe Cipriani is hanging with the wild crowd. The restaurateur, who was out of the country for a year, hit SoHo club Greenhouse with repeat rehabber Tara Reid and a group of pals the other night. They danced and downed a couple of bottles of Dom Per ignon. At one point, Reid — who poses topless in the new Playboy — went upstairs to the VIP area to greet Lionel Richie. But Cipriani clearly needs to build up his stamina. Our source said, “He left be fore Tara, who remained with friends. But Lionel stayed until 4 a.m.”