Sheila Kennedy, wife of Rep. Joseph P. Kennedy, D-Mass., was listed in fair condition Monday at Massachusetts General Hospital, where she is being treated for pneumonia. A spokesman for the medical center said Kennedy, 38, was admitted Sunday and will remain at the hospital for "at least several days." Kennedy, the daughter of a Philadelphia banker and a mother of twin 7-year-old boys, is a Harvard-educated housing expert and consultant to Boston Mayor Raymond Flynn.