Last week, at a book party for J. Michael Lennon’s Norman Mailer: A Double Life, a 900-page authorized biography of the author, who died in 2007, a good deal of literate septuagenarians gathered at Mailer’s old home near Pineapple Street in Brooklyn. It was once on the market for $2.5 million but has remained in the Mailer family, just as the old patriarch would have wanted it.