Irvine Welsh, the Scottish novelist whose Trainspotting gave birth to what became known as Bad Boy literature, is at it again, and his latest, Porno, will feature some of the zany, drug-addled characters who gave the earlier book much of its edge. W.W. Norton editor Amy Cherry, who has shepherded all Welsh's previous seven books to publication here, bought U.S. rights in this one from rights director Jenny Chapman at Welsh's London publisher, Jonathan Cape. She'll publish in the fall, and Welsh will be off again on another of his legendary tours. The new book is about a scam to make and sell a porn movie.