What happens when two or three – make that 20,000 to 30,000 technowhizzes are gathered together in the name of their black art? One answer is that the cellular telephone network siezes up: the San Jose Mercury News reports that on Monday afternoon at Comdex/Fall in Las Vegas, the cellular telephone system became overloaded for nearly two hours, making it almost impossible to place or receive a call; Sprint Cellular, one of two service providers in Las Vegas, normally has 60,000 subscribers, but Comdex overnight added some 40,000 additional phones, and while Sprint added extra capacity in anticipation of the crush, it simply didn’t have enough channels to handle nearly twice the usual traffic, it said.