The Coca-Cola Co. has awarded its promotions and retail account for the summer launch of its mid-calorie cola, whose working name is Coke Ultra, to IPG's Momentum, sources said last week. The shop's Atlanta office will handle the business, which it landed without a review, said sources. Billings were undisclosed. Momentum execs could not be reached. Last month, Coke awarded general-market ad duties for the new product to WPP's Berlin Cameron/Red Cell in New York, sources said. A Coke rep declined comment.