British pop diva Leona Lewis was slapped upside the head while signing copies of her autobiography, Dreams, at a London book shop today.According to an eyewitness at Waterstones' Piccadilly branch,"[the attacker] walked up there with the book, she signed it and, as she looked up, he just punched her. She was running out with her hand over her eye."A statement on the singer’s website declares that “Leona is understandably shaken and apologises to the fans she was unable to meet and complete signings.”PEN has yet to issue a statement but I imagine it will read something along these lines: PEN...